When paradise hides deadly secrets, the truth lies beneath the surface.

A luxury yacht. A dead journalist. A killer who can't afford to be exposed.

When investigative reporter Dominic Davidson is found floating beside his yacht at Dunk Island, the initial ruling is accidental drowning during a solo night dive. But Detective Bec Whitfield notices what others miss — the dive computer shows he never went deep, the bruising is all wrong, and his laptop has disappeared.

Davidson was days away from exposing a corruption scandal that would destroy some of Far North Queensland's most powerful reef tour operators. Now he's dead, his research is missing, and the marine biologist who was his source has gone silent.

To crack the case, Bec and her boss, Detective Senior Sergeant Todd Davenport must go undercover on reef tours, posing as a couple on a romantic island getaway. For two colleagues who've been carefully dancing around an undeniable attraction for a long time, the forced proximity is dangerous in ways that have nothing to do with the investigation.

As they dive deeper — literally and figuratively — they uncover a drug smuggling operation using tourist boats, systematic environmental crimes, and a killer who will do anything to keep their secrets buried.

But when the marine biologist disappears and the body count starts rising, Bec and Todd are running out of time. The truth is hidden somewhere in these dark waters, and retrieving it may cost them everything.

Including each other.