In a remote island hideaway, the new line-up of Legion of Doom are scheming up a plan to destroy the world. They are Solomon Grundy, Sinestro, Dr. Sivana, Mordru, Riddler, Giganta and the Weather Wizard. The villains are engaged in heavy conversation and Mordru is having a hard time getting their attention, so he uses his magic powers to create lightning so as to get all of their attention. After all of them are finally attentive toward him, he tells them they shall proceed, and that the secretary, who is the Riddler, is going to do a roll call. He then does so in the form of Riddles, only to find that each of the supervillains keep using their powers on him, and he begins to think that his job as a secretary is a thankless one. After the roll call, Sivana introduces his incredible Doomsday Machine, which he then activates and tells the other villains that in one hour all life on earth, with the exception of their own, will be wiped out. The other villains are amazed by the device. He then tells them that they will leave clues that will lead the Superfriends to their lair. Giganta asks why they would lead them there, and he says just to delay them, so that they will be lead to believe they can stop them. Mordru then elects the Riddler to be the one to drop some clues for the Superfriends. So Mordru asks what clues Riddler has in mind, and he tells him not to rush him, even though he is a genius, because even Rome wasn't built in a day. Mordru then reminded him that he only had an hour. Riddler tells him he understands but it wouldn't be his best work. He tells him he needs a moment to think. Then it hit him, and he tells them it's a beautiful plan, and that if Shakespeare had had his mind there's no telling how far he would have gone.
Meanwhile, at the Hall of Heroes, the Superfriends are honoring one of the first superheroes there ever was: Retired Man. The heroes attending the celebration are Batman, Robin, Flash, Green Lantern, Hawkman, Huntress, Captain Marvel and Black Canary. Batman gives him a Bulova watch as a token for their appreciation. And Retired Man tells him he wishes he would call him by his old name, the Scarlet Cyclone. But he really hasn't been the same since he tried to stop a speeding bullet, and because of that, he's a bit too decrepit to be a superhero, and that's apparently why his name was changed. Just then, a message came in over the Message center. Robin hands the message to Batman and he reads it. And it reads: The buttons in a secret room, find it and you're free from doom. You'll never make it is what we're betting, 'cause 50 minutes is all you're getting. Batman and Robin then try to decipher the riddle, and Batman finally figures it out, and he thinks that if Shakespeare had Riddler's mind there's no telling how far he'd go. Captain Marvel asks what it all means. Batman tells him that the Legion of Doom has apparently set off a Doomsday Device and they only have 50 minutes to save the world. The Huntress asks where the Doomsday Device is, and Batman says he doesn't know, but they have to find it. Batman tells them all to split up and search the globe, and that if they have anything to report to the others while they are separated then leave the necessary information at the gas station just down the road. The superheroes then disperse, and start searching for the Doomsday Device.
Meanwhile, outside the Hall of Heroes, Sinestro is sabotaging the Batmobile. He runs off unseen before the Dynamic Duo arrive, and they get in their car and drive off. All the other Justice League members leave as well. Black Canary leaves in her motorcycle. Green Lantern teleports himself with his Power Ring. Captain Marvel flies off.
Meanwhile, back at the lair of the Legion, they are monitoring the Justice League's progress from a oval view screen on the floor. Sinestro says that in a few moments Batman and Robin should be looking for some roadside service. Then Mordru tells Grundy that it's he who will see that they get it. And he magically disguises him as a mechanic and his hat keeps his identity safe. They then teleport Grundy down.
Meanwhile, at the service station, which is right across the street from Sagebrush Cantina, Batman and Robin pull up in the Batmobile, and a woman is talking to her friend Alice on the phone and tells her that she sees some weird dudes in capes just pull in. She tells her that one of them has funny Leprechaun shoes. Just then Solomon Grundy disguised as a mechanic asks the Caped Crusader and The Boy Wonder if he could help them. Batman asks him to fix the Batmobile because they are in a hurry. Grundy tells him he'll fix it, he reaches in under the hood and rips out what he refers to as "loose parts." Batman then asks him if he's sure he's a licensed mechanic. Grundy takes off his hat and points to it and says "Sure, it says so right here." Just then Batman and Robin recognize him, and a fight begins, but they realize they are no match for his might, so they leave. Meanwhile, back at the headquarters of the Legion of Doom, Doctor Sivana is excited that the Dynamic Duo will be slowed up for a while. Riddler and Sinestro are working out their next plan. Riddler then pulls his mask down over his eyes and teleports away.
He then begins painting a riddle on a rock: Saving the world is up to you, find your fortune, that's the clue. Green Lantern then spots the riddle after teleporting to that location with his power ring. He reads the riddle, and tries to decipher it, not having a clue what it could possibly mean, until he walks up to what appears to be a Gypsy woman who is a fortune teller, although unknown to Green Lantern, this Madame Lazenga, a Gypsy "woman" is actually Sinestro in disguise! He walks over to him and sits down at the table next to Sinestro. He asks him to read his fortune so as to figure out where he is supposed to go. Sinestro looks into his crystal ball and tells him he's going to take brunette with him on a seven day cruise. But Green Lantern says he doesn't want to. Then Sinestro tells him to make it a blond, because she'd be "dynamite!" Green Lantern tells him to forget about the crystal ball because he has to find out where to go because the fate of the entire world depends on it. Sinestro asks "Why didn't you say so?" and then he tells him he has to analyze his handwriting. He then has GL write down exactly what he tells him: On the sunny side of the street. He then tells him that based upon his handwriting he is certain that he is an introvert that doesn't want people to get to know him. Green Lantern is surprised that he could tell all that from his handwriting, but Sinestro says he was able to discern that from both his handwriting and his mask, which GL then tells him that his mask is his work. Sinestro then tells him he's either a burglar or the Lone Ranger. Green Lantern tells him he's not a burglar, to which Sinestro responds; "Well then give my regards to Tonto." Green Lantern tells him that he doesn't have time for idle chit-chat, because he hasn't much time. Sinestro tells him that the answer is in his palm, but upon opening his hand, he tries to take his ring off and tells him it's quite an interesting ring. Just then, Green Lantern realizes that he has a very interesting ring as well, and that could only mean one thing...Sinestro then interrupts him saying: "We're engaged!!" But it's too late, Green Lantern recognizes now that he's not a gypsy, he's Sinestro. He then cites the Green Lantern Oath, and then Sinestro tells him, "Not bad, but how do you like this one?" He then goes on to quote Mary Had a Little Lamb. And after that he opens fire with his power ring, blasting a yellow ray at Green Lantern, but Green Lantern ducks and the blast strikes the table they were sitting at, knocking it over. Green Lantern then jumps back up blasts a green ray from his ring and it strikes Sinestro knocking him to the ground. Green Lantern continues his search for the doomsday weapon and teleports away with his ring.
Back at the Legion's headquarters, the other super villains are very disappointed in Sinestro. Mordru then teleports Sinestro back with his magic. Mordru yells at him saying that he let him get away, and Weather Wizard asked him why he didn't run after him. Sinestro then runs his hands through his wig and says: "Because it's not lady like." Weather Wizard mocks him, and Sinestro asks him if he thinks he could do better, to which he tells him "Just watch me!" He goes on to explain that by now Batman and Robin are likely looking for a new "set of wheels." He then teleports away.
Meanwhile, Batman and Robin are running down the road, searching for the Doomsday Device on foot, until they come across a used car dealership at the intersection of Lancaster and 1st Street. They both agree that it was quite a stroke of luck, and that they were even a little too lucky, but since so much is at stake, they decide that they will play along and see where it leads, even though they know it's very possible it's a trap. They are then greeted by Honest Al, which is actually Weather Wizard in disguise, and he asks them what brings them there. Batman informs him that he's in need of wheels. Honest Al takes them over to an old Volkswagon. He tells him his mother drove it to church on Tuesdays and Thursdays. Before deciding whether or not to buy it, Batman tells them they have to check it for safety first. Robin then says: "Holy Ralph Nader! We don't have time for safety! The world is going to blow up!" Nevertheless they check it, and upon passing, Batman decides he'll take it, but he ends up being short on cash, so they decide to take a motorcycle that used to belong to a cop from Pasadena instead. They then ride off, and Weather Wizard calls the others and tells them they won't last five minutes on that motorcycle. And needless to say the other villains are very happy with the Weather Wizard's work, and they cheer for his job well-done.
Meanwhile, at the Calabasas Automotive, Alice's friend is still talking to Alice on the phone as she watches Hawkman fly down and land in the lot of the gas station. She tells Alice "You ain't gonna believe what just flew in here!" Hawkman then approaches the Batmobile which is parked in front of the station. He then realizes that Batman must have found out something. Grundy in his mechanic disguise walks out and asks him if he needs any help. He asks if he's seen Batman and Robin, to which he responds "No sir." But knowing he's around there somewhere he starts to head inside the station, telling Grundy he'll look for him himself. But Grundy grabs him. Alice's friend watches the whole thing and tells Alice how the ugly guy just jumped the guy with wings. She tells her she's not coming home for dinner, because she "wouldn't leave this place for a million dollars. I want to see who shows up next!" Grundy ties Hawkman to a hydraulic lift, and raises it up as high as it goes.
While on the road, Batman and Robin are riding their new set of wheels, when all of the sudden the passenger car separates from the bike, leaving Robin riding on nothing but inertia down the road. Batman tells him to try and keep it under the speed limit.
Black Canary arrives at the gas station, and Alice's friends watches her. Black Canary then calls to see if anyone's around, but she says "Hello" so loud that she caused sonic vibrations with her Canary Cry, which cracked the windows on the phone booth. Alice's friend then tells Alice over the phone: "You should hear the mouth on this one!" Grundy, still disguised as a mechanic approaches Black Canary and asks: "Did you call?" Black Canary asks him if there was any messages for her, to which he tells her no. She then asks her if he seen anyone in a cape, with wings or that looked a bit unusual. He tells her she's the first. Just then, inside the station, the bound Hawkman kicks over a gas can. Black Canary asks Grundy what that noise was, and he takes off his hat like a gentleman and tells her he'll go check. But of course once his magic hat is off of his head it makes the recognition of him visible to her eyes...and she immediately attacks him, knowing that he's actually Solomon Grundy. Grundy grabs her by the throat and immediately scoops her up into his arms and carries her inside the station. Alice's friend who's still watching from the phone booth tells Alice what she's missing, telling her that Grundy "got the girl with the big mouth."
And at the lair of the supervillains, they watch from their monitor as Batman and Robin are taking a terrifying ride on their motorcycle of death. Weather Wizard says he hasn't had this much fun since he whipped up Hurricane Hilda. Mordru tells all of the villains to direct their attention to a certain flying captain. And of course he is referring to the Riddler, who is dressed up as a flying captain. Riddler then tells them: "Leave it to me skipper."
Now, Captain Marvel is flying through the sky in search of the Doomsday Device. And on the ground, A happy couple is having a nice quiet picnic lunch in the woods, only to have it interrupted as the Huntress runs through with her crossbow. Meanwhile, Captain Marvel lands and starts following a trail of signs with another riddle on them. The riddle reads: If our device, you wish to find, just look inside, your super mind...and the last sign read: Berma Shave. He then manages to decipher the riddle and realizes that the answer is locked inside his sub-conscious. But at this point he realizes it would take a psychiatrist to unlock his sub-conscious. And just then, the Riddler, disguised as a shrink, along with an office appears in front of him. Riddler disguising his accent to sound British, tells him he was expecting him. He then asks Captain Marvel to lie down, and the superhero then complies. Lighting a cigarette, he asks him his name. He tells him "Captain Marvel." Riddler asks if his parents gave him that name. He tells him in a soft whispering voice, so as not to let anyone else hear his secret identity, that his real name is Billy Batson. He asks what's the deal with Captain Marvin. And then Captain Marvel says "It's Captain MARVEL." He goes on to tell him that the name was given to him by an ancient wizard. The phony shrink asks him to tell him about the ancient wizard. Captain Marvel angrily tells him that he doesn't have time for this, and that he has to help him unlock his sub-conscious. Riddler tells him that it seems he's a victim of an identity crisis, since first his name is Marvel then it's Batson then Marvel again. He tells him in a somewhat Eastern European sounding accent that he's suffering from a classic case of split personality. Captain Marvel then tells him that he's got to save the world. Riddler then tells him he's also suffering from delusions of grandeur. Both conditions of which show signs of Schizophrenia. He tells him of a case of a man named Oscar Heely, a man who was a Schizophrenic, and at times thought he was a woman. He told him he's fortunate because spit personality happens to be his specialty. Captain Marvel starts to tell him he's glad, and then the Riddler angrily, and this time in a Southern accent tells him "Who asked you?!! I am the psychiatrist!!" He tells him never to interrupt him when he's talking. He then tells him to lie there and listen to him. But once Captain Marvel shuts up, the phony shrink returns to his original British accent and asks him how he's supposed to help him if he lies there like a dummy. Captain Marvel tells him he has to find the location of the secret doomsday device and he's only got about twenty minutes. Riddler then realizes that he should toy with him like a cat toys with a mouse, by letting him know he's looking for a lake. Using word association, he asks him to think of the first word that comes to mind when he says: "Water." Captain Marvel then says: "Ocean." Riddler says: "Smaller." Captain Marvel replies: "Pond." Riddler next says: "Tahoe" Captain Marvel then says: "Reno". Riddler is starting to get frustrated, and he says "Salt Blank City." Then Captain Marvel says: "The Blank Tabernacle Choir!" Riddler says: "Veronica" Then Captain Marvel says "Lake." At this point Riddler gets caught up in the game and begins to say the first thing that pops into his mind. He then says: "Michigan." Then Captain Marvel says: "Arizona." Riddler then says "Desert," being the first thing he thought of when Captain Marvel said "Arizona." Captain Marvel then apparently thought of being thirsty in the desert so he said "Water." Then Riddler says: "Lake!" He then tells him that that's it...but just then he realized that it came from his own subconscious and not Captain Marvel's. Nevertheless he tells him that's what he's looking for...a "Lake." (after all Captain Marvel did earlier say it when Riddler said "Veronica") Captain Marvel then says "Ontario." Riddler then says: "Canada." Captain Marvel then replies: "Mounties!" Riddler then realizes what's going on and he tells him to stop, because what he's looking for is a lake. Captain Marvel rushes off, because Riddler tells him there's about a thousand lakes in the area. As Captain Marvel leaves, Riddler starts laughing maniacally and then quickly stops and says: "Next!"
At the island, Grundy is on the monitor, and he asks Mordru when he'll bring him back to the island, because he's getting hungry. Mordru looks at the Doomsday Machine, and tells him they'll bring him back in about ten minutes. Grundy says okay. Alice's friend saw Grundy talking to Mordru, and from her perspective it looked like he was talking to the sky, and she told Alice that Grundy is talking to God, and oddly enough..."God's answering." Captain Marvel then arrives at the station and sees Solomon Grundy and his two captives: Hawkman and Black Canary. He tells Grundy he's not afraid of him, because he's the The World's Mightiest Mortal. Grundy tells him he's mightier and that anything he does Grundy can do better. Captain Marvel says: "Oh yeah?" And then he picks up a tire and throws it as far as he can. Then Grundy throws another tire. And Captain Marvel tells him that his didn't go quite as far as his. Grundy doesn't believe him, so Captain Marvel tells him to go see for himself. Grundy then leaves and tells Captain Marvel to "Wait here." As Grundy runs off, Captain Marvel rolls his eyes, and runs inside the station to free Hawkman and Black Canary. Meanwhile, Alice's friend told Alice that it was hard to tell but she thinks that "The dude in the red suit beat him by about twenty yards." And inside the station, Captain Marvel breaks Hawkman and Black Canary free, and Hawkman asks if he found out anything. He tells them he now knows that the villains' hideout is a lake, but he doesn't know what lake. Alice's friend walked in and said she "Heard the ugly one mention something about an island. Hawkman tells Captain Marvel there's only one lake in the area that has an island, Hidden Island Lake. Using her Canary Cry, Black Canary is able to communicate loudly enough that the other heroes can hear her despite being so far away. She says: "Go to Hidden Island Lake!"
The message reaches Green Lantern, Huntress, Flash, Batman and Robin. Batman and Robin both roll right through the young couple's picnic with the passenger car. The two of them jump out of the way just in time, and the man jumps into the bushes, and jumps back out and points and tells Batman "They went that way." Batman then thanks the man and tells him to have a nice day. The couple quickly gets back to having their picnic, and they toast their glasses, only to have the Black Canary drive through on her motorcycle.
Back at the villains' lair, the evil doers are shocked that the heroes are on their way to their secret island. But Sinestro tells Mordru not to worry since they'll never get there in time. But with so much at stake, they have to find a way, so Doctor Sivana shows him his formula that he invented to take away the Super Friends powers once they drink it.
Later, Sivana, disguised as a young boy, sets up a lemonade stand near Hidden Island Lake, but he put the formula in the lemonade. Captain Marvel arrives first, and drinks it and loses his powers. He tries to fly unsuccessfully. But he desperately attempts to get to the island. And back at the sight of the young couple's picnic, they toast their glasses once again, only to have the Flash stampede through at super speed. Back at the lemonade stand, Green Lantern is the last to arrive and purchase some lemonade from Sivana and it apparently effects his will power in some way, because he can't get his power ring to function. He then runs off. Batman and Robin arrive and the passenger car rolls directly into the lake. They swim back to the shore and find some jetboats and jump in and race toward the island, but Mordru appears in a jet boat of his own and attempts to lead them on a wild goose chase. Flash is also on a boat trying to get to the island, and elsewhere in the lake Captain Marvel and Green Lantern is in a rowboat and Captain Marvel is rowing while Green Lantern plays the role of the captain. Black Canary and Huntress are coming in a pedal boat.
While in the lair, Sinestro, Weather Wizard and Riddler watch on the viewscreen and mock the heroes. Riddler says he will compose a great poem about this and the world will finally have to appreciate him. But Weather Wizard says in three minutes there won't be a world. Sivana and Mordru then teleport in and everyone tells them they were terrific. Grundy and Giganta come in with drinks to celebrate their victory. Riddler then makes a toast to the Doomsday device. They then drink the drinks and notice they taste funny and Sivana asks Grundy where he got the drinks, and he tells him: "From this bottle." It was the formula that was used to take away the Super Friends' powers. Now all the villains' powers are gone as well. Batman and Robin are the first to arrive and they begin Batman fights Solomon Grundy and Robin fights Giganta. Batman punches Grundy knocking him across the room. Mordru screams: "Get Batman!" The rest of the heroes arrive next. And Batman tells them there powers are gone. Green Lantern takes out Sinestro with one punch to the face. Black Canary saves Robin from Giganta by punching her in the face, since Robin felt that he couldn't hit a woman. Weather Wizard holds out his wand at Hawkman and tells him not to come any closer. Hawkman grabs it and breaks it, and then Robin jumps to the ground by Weather Wizard's feet and as Weather Wizard swings a punch at Hawkman, Hawkman grabs his fist and shoves him backward, causing him to trip on and over Robin. Riddler is hiding behind his chair like a coward. There's less then 60 seconds left before the doomsday device is detonated. Huntress attacks Sivana but he begs her not to hit him since he's a scientist. Captain Marvel runs up to Batman, who's still fighting Grundy and asks if he can cut in. Batman lets him, and he takes out Grundy with one big punch to the face, then Flash runs across the room and in the confusion he almost punches Captain Marvel. Robin sends a leaping punch into the Weather Wizard's face and tells Batman he can't find the Doomsday device. Continuing their search, Batman finds where Riddler had been hiding. Preparing to hit Riddler, Riddler begs him not to hurt him, and Batman demands to know where the Doomsday device is, he points up to the ceiling and shows it to him. Batman then shouts "It's up there!!" Hawkman meanwhile, is taking on Mordru...and there's less than 20 seconds left.
Sivana, who is captured by Huntress, begs them not to harm his doomsday device. Batman moves Huntress out of the way, and he grabs his left arm while Captain Marvel grabs his right arm, and the lift him and with his head press the button to shut down the machine, which knocks him out in the process. The machine shuts down with only 1 second left. They then take the villains away, but Riddler sneaks up behind Batman only to get scooped up on his shoulders and carried away.
Hours later, the Retired Man finally arrives at the secret lair of the sinister supervillains. Even though no one's around to hear him, he then declares that he has come to save the world. He looks up at the Doomsday machine up on the ceiling, and he tries to jump up to push the button to shut it down, unaware that the countdown had already stopped. He attempts to jump a few times, until he finally gives up and says: "Oh heck."