In the UK, Detective John Steel is investigating the organization who killed his family. When he comes across information that something big is going to happen on the cruise ship Neptune, Steel goes undercover. He has fourteen days to figure out what is going to happen - and to stop it.

In New York, Steel's NYPD partner, Detective Samantha McCall, is investigating a series of deaths. All seems run of the mill for the homicide detective until they find out that the deaths are somehow connected to the cruise ship Steel is on.

McCall is convinced there is a mole in the department, but can she figure out who he is - and who he's working for? Meanwhile, Steel is running out of options... and the clock is ticking.