Spenser — an ex-cop better known for making trouble than solving it — just got out of prison and is leaving Boston for good. But first he gets roped into helping his old boxing coach and mentor Henry, with a promising amateur. That's Hawk, a brash, no-nonsense MMA fighter convinced he'll be a tougher opponent than Spenser ever was. When two of Spenser's former colleagues turn up murdered, he recruits Hawk and his foul-mouthed ex-girlfriend Cissy, to help him investigate and bring the culprits to justice.