Kate Harper witnesses the prelude to a murder outside her Treasure Island, Florida beach house. Finding a key piece of evidence in the sand, she becomes a material witness to the tragic event.

Unwelcomed visitors and prying eyes descend on Kate's house following a newscast identifying her as a possible key to solving the murder. As the interest in her and her beach house escalate, Kate decides to take matters into her own hands and sets out with a reluctant partner, handyman-surfer Nick Mason, to hunt down the murderer herself.

Kate and Nick wade through a sea of suspects. The closer they come to uncovering the killer, Kate's own life is put in danger as someone in the vacation beach community is intent on keeping her silent.