Boston Detective John Mulligan, 52, was murdered execution-style on September 26, 1993, while on the job one night. Shortly after his death, police arrested 19-year-old Sean Ellis for the murder, alleging that Ellis and his friend Terry Patterson were after Mulligan's gun. This documentary explores how the evidence linking Ellis to the murder has been questionable and how people have long been wary of widespread police corruption and systemic racism that is skewing the case.