After returning from a tour in Afghanistan, detective Billy O'Connor comes home to a Brooklyn he doesn't recognise. As he tries to return to his normal routines, his PTSD is easily triggered and he suffers severe hallucinations. Once he begins to work a gruesome homicide case, however, O'Connor has difficulty sorting out what's real - and after he uncovers some strange clues, he'll have to face the unthinkable to bring the killer to justice.