Spenser (Mark Wahlberg) - 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 (Alan Arkin), with a promising amateur. That's Hawk (Winston Duke), 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 (Iliza Shlesinger), to help him investigate and bring the culprits to justice. Inspired by Robert B. Parker's Wonderland, a best-selling novel by Ace Atkins.