Tom Craven (Mel Gibson), a detective, picks up his daughter, Emma, from the airport. She's visiting from college, and they haven't seen eau other in a long tim, but the happiness is short lived. Emma begins vomits in the car.
At home, Craven begins to cook her dinner, but her nose starts to bleed and she vomits more, telling him she needs to tell a doctor something. As they hurry out to the car a mysterious voice cries out “Craven!” and cuts Emma down with a shotgun blast. She dies in Craven's arms.
Craven identifies her body at the morgue, taking a lock of hair, then sets off to investigate why this happened. He finds a pistol in her nightstand and traces it back to Emma's boyfriend David.
David is terrified that the company Emma worked for, Northmoor, claiming she discovered they were secretly manufacturing nuclear weaponry designed to be traced back to other countries.
Later, Craven discovers a geiger counter in Emma's pack and, by accident, finds the lock of her hair she kept was radioactive. As he burns her clothing, he's approached by Jedburgh (Ray Winstone), a mysterious agent who's supposed to keep Emma's information from leaking. For some reason, Jedburgh lets Craven's search continue.
Craven tracks down another friend of Emma, who tells him Northmoor's president was responsible for the hit on Emma. But he's getting sicker and sicker, and a geiger counter inspection of his fridge reveals his milk has been poisoned.
Now, with nothing to lose, Craven must hunt down the president of Northmoor, avenge his daughter's death, and expose the company's corruption to the nation.