In the Aquacave, Aquaman and Aqualad receive a message, relayed by a signal fish, about a curious object, bobbing on the ocean's surface. Investigating, the pair discover a strange shell box. Inside is a call for help from their water sprite friend, Quisp, along with a map giving directions to his hidden world beneath the sea. Quisp's world is accessed through an underwater cavern, with a labyrinthian channel going ever deeper beneath the sea. Soon enough, Aquaman and Aqualad find themselves in the fantastic underwater world of the water sprites. The magnificent hard water structures of the sprite's city seem deserted. Suddenly, Aquaman and Aqualad are attacked by a trio of sprites, who hurl an immense sphere of hard water at the aquatic duo. Evading the sphere, The two heroes run headlong into a gigantic crab-like creature, prodded by the sprites into attacking. Fleeing the creature, Aquaman and Aqualad cross into a powerful current that draws them into a strange cone-like projection, jutting up from the sea floor. Aquaman is just able to push Aqualad free of the current before he is fully pulled inside the cone. At the bottom of the cone, Aquaman is met by a powerless Quisp. The water sprite criminal, Quirk has invented a weapon that steals the magic powers of the sprites. Quirk, and his criminal gang, have conquered the world of the water sprites, with plans now to invade Aquaman's world. Aquaman telepathically instructs Aqualad to push the cone's funnel in the direction of the crab-creature. Caught in the powerful current, the monstrous crustacean takes hold of the cone, with it's enormous pincers, and shatters it. Freed, Aquaman, Aqualad, and Quisp race back to the "outside" world. There, they quickly catch up with Quirk and his gang. Quirk and his two associates consume some strange edible which causes them to grow to gigantic size.
Ducking into a coral cave, Aquaman, Aqualad and Quisp elude the titanic sprites, now too large to follow the heroes into the caverns. Giving up their pursuit, the giant sprites ascend to the surface. While Aqualad and Quisp continue trailing Quirk's gang, Aquaman alerts the US Navy to the sprite's invasion of their world. Quirk and his gang establish a beachhead on the uninhabited Ropito Islands, where they very quickly have erected their own hard water kingdom. A Naval aircraft carrier arrives to engage the enemy. Quirk and his sprites thunder out into the surf to repel the naval forces. The carrier fires a warning salvo at the sprites. The sprites use their magic to build a mile high, hard water roller coaster track, directly underneath the carrier. After the insane, wild ride has deposited the now battered carrier into the ocean proper, the carrier's jet fighters take to the air. The sprites generate hard water missiles, firing them off from the ocean's surface, keeping the fighter craft at bay. The captain of the carrier has no choice but to admit defeat. The sprites begin capturing passing ocean liners and cargo ships, filling their incredible hard water kingdom with the stolen goods and loot. Aquaman steals aboard one of the soon to be victimized sea vessels, hiding inside a valuable sarcophagus of Asian origin. Once within the walls of the sprite's kingdom, Aquaman quickly ferrets out the weapon Quirk uses to steal the sprite's magical abilities. Aquaman's theft of the weapon is discovered by one of Quirk's giant sprites. The colossal criminal pursues Aquaman beneath the waves. As Quirk's man prepares to launch a bolt of mystic force at the hero, Aquaman suddenly darts to the side. The evil water sprite is caught in the concussion wave of his own force bolt, rendering him unconscious. Returning to Aqualad and Quisp, Aquaman reverses the dial on Quirk's weapon, firing it at Quisp. To Aquaman's horror, instead of returning his magical abilities to him, Aquaman has killed Quisp.
For long moments, Aquaman is awash in guilt and grief, all of which gradually turns to fury. Taking up Quirk's gun, Aquaman prepares to take down the sprites. Commanding dozens of sharks to swim around them, in a formation that creates the illusion, from a distance, that the sharks are a single gigantic shark-like leviathan, Aquaman and Aqualad approach the sprite's island kingdom. They swim the perimeter, hoping to lure the sprite's out into the open, when they come to investigate the bizarre "creature" circling the Ropito Islands. Deciding the gambit has failed, Aquaman disperses the sharks. Out of the corner of his eye, he spies one of the sprites diving into the ocean. Aquaman and Aqualad follow the sprite, now normal sized, back to the hidden underwater world of the sprites, where they watch Quirk's man gather sea weed, pulping it into mash. Aquaman ascertains that the growth effects are temporary, and must have worn off, prompting Quirk to send his man out for more of the strange flora. Aquaman and Aqualad rush the sprite, but he's too fast, leveling them with a mystic force blast. With the heroic duo stunned, the evil sprite moves in for the kill. Suddenly, Quisp appears, taking out the sprite with his now renewed magic powers. Quirk's gun had only thrown Quisp into a deathlike coma, while it revived the magic powers within him. Quisp releases all the imprisoned water sprites. They follow Aquaman back to his world, where they all consume the sea weed mash, growing to enormous size. The sprites then lay siege to Quirk's kingdom. Quirk still has a surplus of the power stealing weapons, though, which he and his gang use to defeat the giant sprite army. Quirk, however, hasn't taken into account an oversize Aquaman and Aqualad, who attack from the rear. Immune to the effects of Quirk's weapons, the towering aquatic duo make short work of the comparatively diminutive sprites. Quisp and his fellow water sprites take custody of Quirk and his gang, returning to their world.