Luke Arnold

After an apparent threat is made on Riggs’s life, the squad is on high alert, but with Murtaugh taking on more responsibility at work, he and Riggs have to deal with their changing relationship. Meanwhile, Trish gets caught up in some trouble, and Molly asks Riggs to make a decision about their future in the second season finale.

Mac and the team have no time to reminisce while visiting Mac's and Bozer's hometown when they immediately start searching for a kidnapped prodigy from Mac's old middle school, Valerie (Amiah Miller). With just pliers and speaker wire available, Mac works doggedly to rescue the young genius he has so much in common with. John Heard guest stars.

Darius vows revenge on the hacktivist group Re/Syst, no matter what the cost. Also, Harris discovers a dark secret and Grace reveals one of her own.

Darius, Grace and Harris uncover the darkest secret yet, and Liam reconnects with Jillian.

The government’s final plans for a doomsday scenario set in motion a surprising chain of events for Grace, Darius and Harris.

Desperate to defuse a nuclear standoff, Liam receives help from an unlikely source. Also, with Darius missing, Harris and Grace take matters into their own hands.