When Detective Bailey's sister, Jess, runs into trouble with the law, Bailey must decide how far she's willing to go to protect her family. Meanwhile, with Trish away on a company retreat, Murtaugh is left to help Riana navigate boy problems, and Riggs deals with the fallout of a night of heavy drinking.
When Texas cop and former Navy SEAL Martin Riggs suffers the loss of his wife and baby, he moves to Los Angeles to start anew. There, he gets partnered with LAPD detective Roger Murtaugh, who, having recently suffered a "minor" heart attack, must avoid any stress in his life.
From the moment the brash and impulsive Riggs meets prudent, by-the-book Murtaugh, it seems as if this partnership is doomed. But after their first case together, both realise this arrangement might just work out after all - if only Riggs doesn't get them killed first.