A dignified actor, Billy Bolla, nears retirement and keeps close watch on his pension book, kept in a sealed bottle. On a cruise among Greek islands, while he's the on-board entertainment, he drops the bottle overboard and Snowball, a white dolphin, swallows it. Billy hires a local guide, Sidik, to help find Snowball, who has other pursuers: it has escaped from the pool of the sadistic Marcov, an arms merchant who's been training Snowball for a suicide mission. Billy and an Italian boy, Theo, who's mom is Marcov's maid, must save Snowball (and the cruise ship itself) from Marcov's deadly plan. They also help Theo's mom and keep their eye out for the pension book.