Synopsis
Our story begins with a trial. We see Bruce Banner on trial in Atlantis, an undersea kingdom, for crimes he didn't commit. We flash back and find out that Bruce and Rick Jones get jobs on the "Gamma Drilling Platform" in the Atlantic ocean. They use the aliases of Mr. Keenan and Kel, which Bruce doesn't understand why it's funny.
The workers of the Gamma Drilling Platform have been using a drill which emits Gamma radiation to drill for oil. Little do the drillers know, the gamma radiation has changed some of the sea life into gamma mutants. The sea mutants attack the sunken city of Atlantis. Above, Bruce and Rick (and of course Monkey) sneak out and try using the Gamma Drill to cure Bruce of being the Hulk. Bruce gets in a cage and is dropped into the water beneath the Gamma Drill. Just as Rick is about to zap Bruce, Prince Namor grabs Bruce and drags him to the surface where he attacks him. Rick tries to stop the fight and happens to put his hand on Namor's shoulder. Namor is offended by being touched and slaps Rick, knocking him to the floor. Bruce gets angry and turns into the Hulk.
Hulk and Namor fight and end up sinking to the bottom of the ocean floor. Rick and Monkey grab an undersea vehicle and go down after them. Rick and Monkey's ship is attacked by a huge gamma starfish. Just as things are looking badly for Rick and Monkey, people of Atlantis show up and rescue them. Rick and Monkey are brought to a chamber where we find that Hulk has changed back into Banner, and is on trial for changing sealife into gamma mutants. Rick is now acting as Bruce's "defender" (which in itself is a wink at a group of heroes including Hulk). Rick tries his best to explain why what has happened to the sealife was not Banner's fault but in fact the people who took Bruce's gamma research and made the drill. Namor will hear none of it. So, Rick questions Bruce in a manner to upset him and make him angry. Banner Hulks out and Rick explains that Bruce cannot control the Hulk anymore than Bruce can control what others do with Bruce's gamma research. Namor agrees to let them go if Hulk will help drive away the sea mutants. So, Namor, Hulk, Rick and the Atlanteans drive away the sea mutants. The mutants revert back to their normal selves.