After the city's gun buy-back program is robbed, the team is on a hunt for those responsible. Meanwhile, Murtaugh walks on thin ice with Trish, Riggs finds an unlikely friend in Ruthie, and Captain Avery is reunited with a college "frenemy" who has key information about the case.

The duo sets out to unlock a case about a veteran hitman who Murtaugh has followed for years. Meanwhile, Riggs struggles to find a connection with his father, Murtaugh scares Riana with his overprotective driving lessons, and the team finds themselves wedged in a dangerous incident that tests their trust.