The Brain approaches Atlantis in his submarine, preparing to conquer it via his sonic brainwave weapon. Aquaman arrives to battle the Brain, and deflects the villain's missile attack. When Aquaman attempts to call marine life as reinforcements, the Brain uses his sonic brainwave weapon to override Aquaman's control of them.
With Aquaman cut off from help, the Brain dispatches his minions to attack Aquaman. Aquaman is stunned and Aqualad is captured and brought aboard the submarine. The Brain uses a treatment to turn Aqualad into his slave, then sends him back out to attack Aquaman. Aqualad is returned to normal after Tusky the walrus hits him on the head. Aquaman then calls for help from a pair of whales that destroy the Brain's sonic brainwave weapon, causing his sub to explode.