A deadly attack. A stolen weapon capable of immense destruction. Something unspeakable just washed in with the tide ... Forensic anthropologist Tessa Nielsen and her daughter are enjoying a day at the beach when a young man's body washes ashore. When Tessa discovers he's been murdered, she realizes this is no day at the beach. The killer is still out there, and Tessa's daughter may have witnessed something that puts her life in danger. Coast Guard Investigative Service special agent Finn Walker is assigned to the case. As he and Tessa work together to find the killer, they must also locate a missing weapon that could threaten countless lives. But the more they uncover, the more dangerous the investigation becomes. With a ruthless killer on the loose and time running out, Tessa and Finn will have to risk everything to stop a catastrophe ... and stay alive.