Riggs is reunited with childhood friends and comes to realize they might be mixed up in the robbery-homicide case he and Murtaugh are investigating. Murtaugh finds a joint stashed in his kitchen that he brings to Scorsese for testing in effort to bust one of his kids.

After a mansion break-in turns into a homicide, Murtaugh and Riggs set out to find the culprit. Murtaugh and Trish question their trust in Riana as she gets into some trouble with new friends. Riggs recalls his troubling childhood and finds a true family with Molly and Ben.