A flaming rag beckons to fourteen-year-old Finnish Mikael and his sister Marjatta from a porthole of the Red Dolphin and, drawing their fishing boat closer, they are rammed by the bigger craft, pitching them into a tense, pungent adventure. Struggling to the deck of the yacht, they're stumped by the man imprisoned below--he doesn't know the yipping terrier or his own name or how he got there; and they're further stymied when, after grounding the leaking boat on a strange island and sleeping on the beach, they awaken to find that their clothes are gone. Seems that islander Timo, alerted by radio, assumes that they've stolen the missing-from-Sweden Red Dolphin and is hell-bent on claiming the reward--ergo the clothes spirited away, his appearance with a gun, his impatience when Marjatta tries to doctor the adder-bitten dog, his clapping the children in a fish shack. But help comes from his father-in-law Elias, who has his own reasons for wanting a share of the reward. With the mysterious ""Gustav"" and amid much heaving and breath-holding, they get the yacht afloat just as Timo returns. . . and what follows is in the best tradition of film chases. Maybe you've guessed the outcome: ""Gustav"" (obviously a person of consequence) is the also-missing yacht owner suffering from amnesia--which, plus his later largesse, is a lot to swallow. But the Baltic presence is immediate and enduring--even to the youngsters, who turn aside the reward.