初三三班最调皮的“学渣”王强和“暴躁班主任”石妙娜意外互换了身体,压迫已久的王强过了一把当班主任的瘾,石妙娜也体会到了做“学渣”的滋味。石妙娜的公开课比赛日期临近,二人急需找到换回身体的方法,却遇到重重阻碍……。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.。