After the fatal end to an argument on a construction site, the squad works to untangle facts about the incident. Meanwhile, Riggs struggles to rekindle his relationship with Molly, Trish's job is on the line as she tries to close a big deal at work, and Murtaugh gets one last chance to make it right at home.

When Riggs and Murtaugh attend Leo Getz's surprise wedding, they end up investigating a missing person. Then, Riggs comes face to face with someone from his past and Murtaugh receives news that might change his life forever.