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.