Detective Sam Dietz is paired with a shady FBI agent to track down another serial killer terrorizing Los Angeles.

Sam Dietz is a relentless cop who is trying to get over a serial killer's attack on his family in the last Relentless film. He is also trying to find the new killer in the city. Gregor is a relentless patriot who is trying to avenge the deaths of his family. He hunts down those responsible, and executes them one by one. The two men learn to understand and even respect each other in this violent tale of cat and mouse.—Sean Kilby and Jason Parker <[email protected]>

L.A. Detective Sam Dietz, struggling to emotionally survive his last big case (in the first Relentless film) is unwillingly paired with a shady FBI agent Kyle Valsone into tracking another serial killer who kills seemingly at random. But every time Dietz gets a lead, Valsone gets in the way and somewhat throws off the investigation. Suspecting more than meets the eye, Dietz goes around the law to learn the identity of the killer and find out what Valsone is hiding and his connection to the killer. Meanwhile, Dietz's wife Carol now estranged from him due to his long hours, tries to deal with her current situation and their uncertain future.—Matt Patay