Chapter 1: The Sea Beasts from Atlantis
Aquaman and Aqualad happen upon a ship being attacked by strange beasts. The beasts destroy the ship, but ignore the crew who escapes. As they battle one of the monsters, a signal fish alerts them to trouble in Atlantis. Aquaman and Aqualad go to the city, even thought the beasts are still on the loose.
In Atlantis, they learn from Stamar that the beasts originated from the plains around the city. As long as the beasts have their diet of volcanic plants they are docile, but a blight wiped out the plants. Now they are running rampant. Aquaman and Aqualad go to find replacement plants.
When they reach the spot where the plants should be, the hillside is covered in volcanic material. They dig down, with the help of an army of fish, only to discover that the plants here are also gone, apparently pulled out from the inside...
Chapter 2: Doom on Clay Island
They culprit is Quisp, who pulled out the plants to help a horiculturist named Captain Clay. But Aquaman recognizes Clay as a sea raider, and suspects he knows what the Captain is up to. Quisp goes with them to help as they go to spoil Clay's next attack.
Quisp scares off Clay while Aquaman and Aqualad chase off the monster and search the ship that was targeted. They find some of the plants on the ship. They then follow Clay, using a network of fish, to his hideout.
Quisp distract Clay while Aquaman and Aqualad go to retrieve the plants so Clay can't control the sea beasts. Unfortunately, Clay had planned for this possibility, and Aquaman and Aqualad are caught in a trap with a signal device. Clay sics the monsters on the pair, as Quisp protests.
Chapter 3: Prisoners of Atlantis
Quisp uses a wave to wash the plants out to sea, and the beasts follow their food. Quisp feeds them as Aquaman and Aqualad attack Clay. They trade places, Quisp to deliver Clay to the authorities, while the Aqua-duo take the beasts back to Atlantis.
But all is not well in Atlantis. They are given a decidedly unfriendly welcome by the city guards. Stamar rushes free when he seas the pair, and they take him to safety. Stamar explains that Pomoxis has taken over the city, and informed Captain Clay of how to control the sea beasts. Clay gave Pomoxis powerful weapons in return, which made the takeover possible.
Aquaman, Aqualad, and Stamar sneak into the city but are caught by Pomoxis. He throws them into the air dungeon. A pump replaces the water with air. Aquaman takes some of the sea beast's plants and gets a fish to make a trail of them to the dungeon. The sea beasts attack the dungeon. Now free, Aquaman quickly takes out Pomoxis' guards and frees the city once more.
The cover is another classic, with Aqualad's speech balloon using one of the more amusing Aqua-expressions: "Great Guppies!" What's so great about guppies, I gotta wonder...
This city of Atlantis was settled sometime in the past, and they scouted out the location for it. The Atlanteans refer to our oceans as another world.
Why would any pirate work the sea when they know that any fish might be a spy for Aquaman, ready to inform him of the location of their hideout?
A nice bit of continuity (besides the appearance of Quisp) is the reappearance of Pomoxis, who, as you recall, took over Aquaman's place in issue #3. Pomoxis isn't terribly smart, though. He throws Aqualad into the dungeon with a full bag of the plants that control the sea beasts.
Shorts in this issue: one-page "Our Underwater Friends" cartoon, one-page "Shorty" cartoon, one-page "Superstitions of the Sea" text piece, and a one-page public service cartoon on appreciating the arts.
Another great Silver Age story with typical Silver Age elements, and a plot that actually holds water.