Lucas Davenport and Virgil Flowers join forces on a deadly maritime case like no other...

An off-duty Coast Guardsman is fishing with his family when he calls in some suspicious behaviour from a nearby boat. The slick craft has stopped to pick up a surfaced diver, who was apparently alone, without his own boat, in the middle of the ocean. None of it makes sense, and his hunch is proved right when all three Guardsmen who come out to investigate are shot and killed.

They're federal officers killed on the job, which means the case is the FBI's turf. And when the FBI's investigation stalls out, they call in Lucas Davenport. But when the case turns lethal, Davenport will need to bring in every asset he can claim, including a detective with a fundamentally criminal mind: Virgil Flowers.

In a case like no other, Flowers and Davenport will need to work together to catch the killers – before they become targets themselves.