After a fiery explosion kills their trusted FBI partner, Special Agent Elaine Bishop's life is thrown into jeopardy, along with her tough-as-nails partner, Agent Mike Weber. Their covers blown, and a drug dealer orders a target on their back. In an instant their lives become terrorized. They agree to a covert mission using a fake marriage as their cover and are whisked aboard a seven-day cruise traveling to the Western Caribbean. Posing as a honeymooning couple, they board the cruise ship with a newly appointed FBI agent named Franklin Knight.
They dive into their assignment investigating missing women and so-called accidental drownings, that threatens to ruin the ship captain's reputation. His own security officers have failed at discovering the source. When Agent Bishop disappears on the twelfth deck's walking path, Agent Weber combs the ship like a madman in search of her. Once he finds her, he becomes her twenty-four-hour protecter and seeks to flush out her stalker. Agent Bishop worries every corridor poses a threat, but within Weber's arms she finds a safe haven. Soon the three agents discover a sinister conspiracy onboard involving human trafficking and border infiltration. Will they learn the stalker's identity before he intervenes and destroys their chance of forever?