夏洛克·福尔摩斯卷入了一场涉及宿敌莫里亚蒂教授的邪恶阴谋,最终与一位母亲最近被谋杀的年轻美国土著妇女阿米莉亚·罗哈斯联手。在他们合作破案的过程中,阿米莉亚也开始证明这位大侦探就是她失散多年的父亲。
While rowing out in the ocean, Mitch rescues an underwater photographer, named Linda, floating on some wreckage. Linda's somewhat disjointed, frantic story about something attacking her in an underwater cave which killed her partner and destroyed her boat is misconstructed by Kay Morgan, an ambitious, publicity seeking newspaper reporter, who creates a media frenzy by starting rumors about a "creature in the bay." Harvey Miller, the new lifeguard and prankster, benefits from the events by selling undersea creature T-shirts. Meanwhile, Shauni rescues a young girl from drowning and soon becomes compelled to rescue the girl, her brother and their mother from the life they live in the slums of South-Central L.A., much to Eddie's chagrin. While Shauni deals with her possessive father who disapproves of her lifeguard job, Mitch also pressures Captain Thorp to ask for funding for new advanced motorboats, called Scarabs, for the team.