A Boston police officer goes to Nantucket to investigate the murder of his partner, but he finds more than he bargained for.

When Boston homicide detective James Doyle's partner is killed in an ambush, her dying words provide him with a clue that sends him to the remote island of Nantucket. There in the grey off-season when streets are empty, his hunt for the killer leads him to the heart of island where not even he can hide from the truth.