An attractive wild young woman, named Mattie, and her plain twin sister, Gwen, arrive at the beach and vie for Mitch's affections. But Mitch is unaware that Mattie and Gwen are the same person, a woman with split personalities which soon lands Mitch in danger when Gwen's other personality, Mattie, means him physical harm.

While on her way to her grandmother's birthday party, Alex's day gets sidetracked when she tries to save a diamond runner, named Ben, whose partners, Lisa and Jason, want to silence him for good which leads to a standoff in an underwater cave with Alex and Ben trying to avoid the rising tide and the smugglers circling above in their motorboat.