In the middle of the Atlantean night, Aquaman leaves for a secret meeting in Washington DC. There he learns that the Ocean Master is threatening the world.
In a flashback we learn that Aquaman and Aqualad tangled with Ocean Master in a Fjord, when he was using a robot to hunt whales. They learned from Captain Burke, who saved them from Ocean Master's ship, that Ocean Master has been deploying robotic hunters, and raiding cargo ships and coastal villages. Every navy in the world is hunting him.
And now, in Washington DC, he has sent evidence of his powers, and intends to blackmail the world.
Aquaman and Aqualad go to investigate the ship Ocean Master stranded on an iceberg to demonstrate his powers. As they arrive, the iceberg breaks up. They dive into the water, but see no sign of Ocean Master or his ship. Only a lone sperm whale on migration. They search in wider circles, and see the whale again.
And also see what appears to be underwater snow. They follow it up to the surface, where it is blocking the entrace to a harbor. Aquaman calls in some finny friends to take care of it, then follows the suspicious whale.
He finds that the whale won't obey him, and seems to have a strange patch on its underside. As they study the problem, the Ocean Master's ship appears and fires on them. Ocean Master catches them in a net-torpedo.
Ocean Master gloats and reveals his whole plan to them, including the fact that the innocent whale has been operated on and is causing the various disasters. He puts Aquaman and Aqualad into one of his automated killer craft, which the various Navies are all gunning for. The craft surfaces, and the ships start shooting at it...
Aquaman and Aqualad escape by triggering the harpoon controls on the craft, which halts the vehicle and throws them out. Aqualad tells Aquaman that they can signal the Navy to destroy Ocean Master, but Aquaman tells him that all they will do is take care of the whale.
Aquaman manages to tame the whale, and aim its destructive powers at the Ocean Master's ship. The ship wrecks, and Aquaman and Ocean Master face off. They battle, but Aquaman doesn't really fight back.
Above the battle, the navy has located Ocean Master's ship, and bombs it. Aquaman goes to stop the bombing, and get the Navy to chase the whale. Then he admits to Aqualad why he wouldn't fight Ocean Master.
Ocean Master is Aquaman's younger half-brother, by a different mother. He wasn't born a water-breather, and always envied his older brother. He was already headed for a life of crime when he lost his memory in an accident.
They find the whale trapped in rocks, and remove its destructive mechanisms.
Ah, the first appearance of the Ocean Master! The cover must've looked like any other wierdo attacking Aquaman, but the story inside changed Aquaman's future direction for good.
Aquaman was alone in Washington DC, then Aqualad joined him for the excursion to the iceberg. I won't question how.
Aquaman didn't know Ocean Master was his brother until they were captives on his ship and Aquaman saw Orm's face reflected in the ship's plot board. After that he couldn't bring himself to harm Ocean Master.
The letter column continues this issue. The title? "More Mail -- No Title". Eight letters, on a variety of subjects. The first three ask for more Aqualad, and the last five comment on individual issues.
Shorts and notable ads in this issue: a one-page cartoon ad for "Agent Zero" spy products, a half-page Direct Currents column, and a half page "Cap's Hobby Hints" cartoon.
This story is reprinted in Best of DC #10 (Mar 1981).
A good story with lasting impact on Aquaman's universe.