Wormingham is having a masquerade ball, and Bert wants to ask Crystal to be his date. But Wormaline's plans to go to the ball with Burt herself may interfere.

Calling themselves "The Three Fishketeers," a trio of adventuresome fish set out across the ocean floor to seek fame and fortune. Toby, bright-eyed and spunky, Finner, aristocratic and thoughtful, and Gillis, a big "galumphing" guppy who calmly takes everything in stride. Meeting a "damsel" clearly not in distress, the would-be heroes comically try to help her recover a large pearl. But it isn't long before all four of them are swimming for their lives, and The Three Fishketeers finally learn what heroism really is.