At a local Shopping Center, a man named Chuck Nelson and his 14-year-old daughter Jenny, have just finished grocery shopping. While walking across the parking lot to their car, Jenny asks her dad why it seems that fathers by more groceries than mothers. Chuck tells her that he'll have her mother explain it to her when she gets back. Just as they put their groceries in the car, Jenny notices a friend of hers on his bike from across the parking lot. She waves at him and says: "Hi, Jimmy!" Her father asks who he is and she tells him his name is Jimmy Nolan from her math class. He tells her he thinks he likes her. She irritatingly says "Daddy?!" Just then a boy notices Jimmy's bike parked on the sidewalk of the Shopping Center and he then steals it. Jenny notices and tells her dad that he should do something about it. He tells her he doesn't want to get involved because he can't afford to. She tells him he's afraid of the police. He tells her he doesn't want anything to interfere with them being a happy family again, because he just got out a prison.
Meanwhile, at the High School, Andrea Thomas and Cindy Lee are conducting an experiment in chemistry, while Rick Mason enters with a newspaper he's reading. And Andrea tells him she can see that he seems to be seriously studying the sports section. But he tells her he's studying the travel section. She asks if he's planning on going somewhere, and he says a vacation to the South Seas would be nice. She realizes he must have seen the same adventure movie she had seen the night before. He tells her she should have been a detective. Cindy tells her that if she was a detective, she could solve the mystery of all the mysterious burglaries around town. Andrea didn't know what she was talking about so she told her she heard it on the radio. Tut cocked and repeated Andrea's words. Rick tells her it was in the papers, no clues to the thieves whatsoever. Andrea tells them they probably are from out of town, because she doubts anyone from their hometown could pull off such masterful burglaries. Rick tells her she's already talking like a detective again.
Later, at the residence of the Nelson's, a man by the name of Tom Jenkins pulls up and parks his car, and greets Jenny, who is in the front yard. He asks her if Chuck Nelson lives here, and she says yes, and he asks if he's home. She takes him to him, bringing him to the back yard where he's cutting the grass. Tom tells him he's from the insurance company. Chuck looks at him as if very irritated and tells him he remembers him. Tom tells Chuck he has some questions to ask about burglaries that concern his company. Chuck tells him he can't help him with that. But the insurance man tells him he thinks he can, because the burglaries were done in the same style that he used to do them, industrial diamonds with no clues left behind. He told him he knows nothing about the burglaries. The insurance man tells him he may not but it's his job to ask. He tells him if he talks to the police they may actually finally have someone they could put on their list of suspects. Chuck tells him the night of the burglary he was home. He said his wife is out of town and he was spending time with his daughter. Tom asks him if he ever left the house, and he tells him no. After the insurance man left, his daughter walks up to Chuck and tells him that he lied to that man, because he wasn't at home that night. He tells her he had to tell him that, or else he'd be a suspect. He tells her it was that insurance man that had him sent to prison. His daughter is upset with him for lying, and she storms off into the house.
Later, outside the school, Jenny and Cindy are sitting at a picnic table. Cindy asks Jenny why she isn't eating her lunch but she doesn't wanna talk about it. Andrea heads toward them, and Cindy tells her she can talk to her about it, because she talks to her about her problems all the time. Andrea greets the girls, and asks what's going on. Cindy tells her Jenny has something to say. Cindy leaves so that they can talk about it. She asks her what she would do in a situation where she thinks that someone she loves is involved with something terrible, but she's not 100% sure. Andrea tells her if she's not sure, then give whoever it is the benefit of the doubt. Jenny finally tells her it's her father she's worried about.
Later, at the Shopping Center, while leaving, Andrea is talking to Rick about the situation with Jenny's father. She said he served his time and now he's a free man. She tells him about the last time she saw him at the PTA meeting, he said he never wanted to leave his wife and daughter again, and by the way he expressed himself, she believed him. Rick says he hopes she's right, and that he doesn't do anything to screw things up in the future.
Jenny is walking home with a bag of groceries in her arms. She meets her dad on the sidewalk and he helps her with the bag, she tells her she's going to make him a terrific dinner, and he tells her he's glad that she's changed her mind about him. He then tells her she can cook the dinner at Lake Horton, because they're going to have a little vacation in the woods. He accidentally drops his wallet and she sees it's full of money and she asks where it all came from, he tells her a friend of his paid back all that he owed to him. She isn't sure she believes him, because she thinks he's trying to runaway. But he tells her he just wants to get away for awhile. They get in the station wagon and drive off.
Meanwhile, at the school, Cindy tells Rick and Andrea that Jenny's not in today. Rick asked if she called in sick. She tells him no, because she already checked with the office. Andrea tells them they should just head over to her house.
They arrive in Rick Mason's car at the house and she rings the bell but no one answers. She tells them she'll ask the next door neighbor, Mrs. Case, if she knows where they are. Cindy asks Rick if he thinks something bad has happened. He tells her there's probably a perfectly logical explanation for the whole thing. But Cindy has her doubts, because they were supposed to do homework together the night before and she never even called. Cindy returned to the car and tells them that the neighbor lady said that they left town on what she assumes was a camping trip. Cindy told her she thinks that Jenny has told her she had went camping with her father before, but she can't remember where. They all get in the car and drive off, and just as they get back to the school, Cindy remembers where her dad took her camping. She tells them it was at the north point of Lake Horton. Andrea tells them to go ahead into the school. Andrea runs off to a spot where she's unseen, except by Tut, who's in a nearby tree, and then she says: "Oh Mighty Isis!", then she is transformed into the superhero known as Isis! She then flies of toward the lake.
Meanwhile at the lake, Chuck tells Jenny he's going to cook her the best steak she's ever tasted. She tells him she really isn't hungry. He asks her if something is still bothering her. She tells him that she can't stop thinking about how he lied to the insurance man, she then asks where he was that night. He tells her he was out walking and thinking. She starts to talk again and he shuts her up by telling her he doesn't want to hear about it again. She then takes off towards the woods so she can take a walk and think as well. During her walk, she trips on a log, and her and the log both roll down a hill, and the log pins her leg and she can't get up. She begins to call for help, Isis, flying above, hears her and comes to her rescue. She uses her super strength to lift up the log, and the girl thanks her. Isis tells her that she needs to have faith in her father. The girl tells her she'd like to, but she's not sure. She tells her sometimes things aren't what they appear to be, and she has to give him a chance. The girl tells her she'll try.
Back outside the school, Cindy tells Rick and Andrea that everything's okay between Jenny and her dad. She then tells them they are all invited to their home for a Barbecue on Saturday.
While at the Nelson home, Chuck is working tightening the belt on the generator of his car and the insurance man pulls up in his car and asks Chuck if he could give him a hand. Chuck asks what he's doing here, and Tom tells him he doesn't know if he's involved with the burglaries or not, but he's only interested in catching the guilty man, Chuck then asks how he could help. He tells him that his company insures many diamonds, and he asks for his expert opinion as to where the thief might strike next. He then asks him "Isn't this police work?" Tom tells him he'll fill Sgt. Connors in on the details. He tells him he should probably talk to his friends about it first, but he agrees to help him out.
Later in the back yard, Rick, Andrea, Cindy, Jenny, Tom and Chuck are having their barbecue. Jenny realizes that Tom believes in her dad, and she tells Cindy and Andrea she wants to believe in him too. And then Andrea tells her to just keep on believing. Chuck shows Tom paperwork he was working on which shows every company that's most likely to be burglarized. He tells him the Landon Company is most likely the next target. He tells them they have an easy alarm system to knock out. He tells everyone that he'll have the police stake the place out and they'll do the rest. The thief has been making hits every two weeks and he's just about due for another.
Back at the home of Chuck Nelson, him and his daughter are walking outside and he tells her he's going to the Peterson Company. But she tells him he earlier said it was the Landon Company. He tells her he knows it will be the Peterson Company, and he lied because he wanted to catch the thief himself. He tells her to trust him.
Meanwhile, at the Landon Company, Andrea and Rick are talking to Connors and Andrea asks him if he's seen anything suspicious. The cop tells her no, and he wonders if they got the right place. Rick chimes in and says he's not sure if he gave them the right information. Andrea wonders why he wouldn't. He tells her they better call to find out.
At Peterson's, a man in a trench-coat is putting his hands in black gloves, he exits the vehicle with a briefcase, and he unlocks the door and enters the building. He approaches a safe and opens the brief case and gets diamonds out of the safe and puts it in his briefcase. Just then, Chuck enters the room to catch the thief in the act. Chuck then sees the face of the thief...it's Tom Jenkins! He tells him hello, and that everything is so clear now. He tells him his job is fast and efficient, a clean job. Tom thanks him and takes it as a compliment, coming from an expert.
Meanwhile, at a phone booth, Andrea is talking to Jenny and she fills her in on the situation and she hangs up and tells Rick. She tells Rick to have Connors men move over to the Peterson Company. Rick then rushes off to tell them, while Andrea runs off somewhere unseen to turn into Isis.
At the Peterson Company, the two men walk outside and Tom asks if he really thinks that the police will believe him. He tells him he'll take his chances. He then tells him to hand over the diamonds, so just as Chuck reaches his hand out to take them, Tom slaps some handcuffs on him and tells him he's the hero now. He tells him that as far as the police are concerned, he caught him red handed and he'll go to jail while he retires a rich man. He puts him into his car, then Isis arrives and tells Tom to stop. But he tells her he's caught the burglar. She tells him he's a liar, because she had overheard them talking before he knew she was there. He jumps into his car and speeds off. A police car speeds off toward his car and blocks his path. Isis commands the car to "Rise." And the car rises off the ground. She sets it down where the police pull him out of the car and arrest him, and they rescue Chuck.
Later, at Chuck's house, Chuck tells Rick, Andrea, Cindy and Jenny that his wife just called and said she'd be back by noon tomorrow. He then tells Jenny that he finally got a job and he starts next week. Jenny then tells her dad that she's sorry she didn't believe in him. The two of them embrace each other. He tells everyone it's time to serve his World Famous Hamburgers. As everyone else sits down to eat, Andrea asks Rick if she could help him paint his apartment now. Rick then tells Chuck they better make their hamburgers to go.
The title refers to a Leopard, an animal which cannot change its' spots. Some people hold the belief that humans are the same way, that once bad always bad, but this story shows that an ex-con, Chuck Nelson, made a change in his life, and is now one of the good guys.
- This episode started shooting on July 8, 1975.