A saboteur has just blown up a building, and Aquaman and Aqualad are being attacked by squads of fish on their way to Alaska. While battling the confused and weak fish, Aquaman and Aqualad get an assist from Phil Darson. He explains that something is killing the fish. He leaves them to get on with their business, a meeting with Professor Davidson, one of the top oceanographers.
Professor Davidson explains that he thinks pollution is driving the fish mad and killing them. But the local factories won't assist him since a factory was sabotaged, and a night watchman killed. Even as they speak, an explosion rocks the building, and Aquaman races to try an catch the villain. The saboteur sees him coming, though, and blasts him with a missile. He isn't badly hurt, and Aqualad takes him to the surface. They agree to start searching for the pollution in the morning.
The next day, as Aquaman and Aqualad start their search, a crooked factory owner, Mr Leland, claims that the explosion was the result of a malfunction, not a saboteur, so the police won't investigate and learn that he's dumping chemicals into the ocean.
Meanwhile, in Atlantis, Mera and Vulko are confronted by Ocean Master bearing a flag of truce. Mera goes out to see him, and he insists on speaking with Aquaman. She doesn't dare tell him that Aquaman isn't around, in case this is a ruse to see if the city is unprotected...
Aquaman and Aqualad have started to piece together the mystery. There are signs of pollution at both the destroyed factories, and they see that the second factory owner is hiding the fact that a saboteur hit his factory. Aqualad wonders if the professor is involved, but Aquaman doubts it.
Aquaman looks for the saboteur, while Aqualad watches the professor. Aquaman sees the saboteur and follows him, while the professor makes a discovery and leaves with Aqualad following.
The saboteur enters Leland's factory and confronts Leland himself. The saboteur explains that since his request a week ago to stop the pollution was ignored and told it had no legal basis, the saboteur is now using illegal methods to stop the pollution. Aquaman prevents the saboteur from killing Leland, and a fight ensues. In the end, Aquaman is left in the burning factory while Leland, armed with a gun, pursues the saboteur.
Aqualad follows the professor to Leland's home, and watches as the professor rings the doorbell repeatedly, then leaves.
Aquaman wakes in the burning factory, and hears a gunshot. He finds his way out, and sees Leland and the saboteur fighting on a cliff. They go over, and he investigates. The saboteur is still alive, and he reveals himself to be Phil Darson. He explains himself to Aquaman as he dies.
Aqualad learns that the professor had finally proven that the pollution was coming from Leland's factory, and had only be going to confront him with the evidence.
Phil Darson was last seen in Issue #43, in the land of the slow moving giants.
We don't know why Ocean Master showed up outside Atlantis, but it's a nice little set-up for future stories.
This story is reprinted in Adventure Comics #501 (Jul 1983).
A solid read, with nice use of continuity.