Billionaire Jordan Braddock is given blood after a plane crash. The blood came from an employee in Braddock's vast empire, a test car driver by the name of Ben Richards. Because the old man recovers and grows younger, the doctor performs tests on Ben's blood and discovers that Ben is immune from all diseases, and even from aging. "You're practically immortal," the doctor tells Ben. As the effects of Ben's blood begin to wear off and Braddock begins to age and grow ill again, he realizes that he must keep Ben nearby as a personal fountain of youth, so he devises a plot to kidnap the test driver and fake his death so no one will look for him.
Ben hides out in an illegal mining camp, thanks to a teacher who gave him a ride away from his pursuers. A gifted young student at the camp loses his grandfather to typhoid because the greedy mine foreman would not seek medical help for fear of the camp being shut down. The student begins to show symptoms of the disease himself, but Ben is unable to help because Maitland's men have traced him to the camp.
Ben is jailed on a trumped-up traffic charge. The sheriff in town is a dishonest tyrant, building a resort with jail labor under the pretense of constructing a "youth camp." The sheriff also holds a secret over a local woman, and the woman enlists Ben's help to get the incriminating file from him.
A car wreck in front of Fletcher is staged to make Maitland think Ben is dead. Another rich man has learned about Ben's blood and has no trouble in capturing Ben and spiriting him away to a foreign country, thanks to a beautiful accomplice. Surrounded by jungle and guards, Ben has no way out.
Ben is thrown clear of a car wreck with the wallet of the driver in his hand. Fletcher keeps vigil on the search of a river for the car, forcing Ben to assume the identity of the dead man. Unfortunately, the man Ben is pretending to be is a Pennsylvania policeman, who is seen with contempt because he is in town to take the town's popular doctor (who is in actuality a fugitive) back to face charges.
Ben goes to Ohio to look up the man who once gave board to Ben and his brother when they, as children, ran away from the orphanage. Ben's friend is charged with assault, which could be increased to murder if the boy he's accused of injuring dies. Ben wants to give the injured boy a transfusion to save his friend from jail, but Fletcher shows up, shoots Ben with a tranquilizer dart, and whisks him away.
While trapped in a cabin during a snowstorm, Fletcher and his captured prey, Ben, reminisce about Jordan Braddock, the first man to encounter the benefits of Ben's blood. A friend turns Ben in, but Ben manages to escape from Fletcher in Braddock's limousine--with Braddock as a passenger. The old man is critically ill, and Ben offers to get him to a hospital, and even to give him a transfusion to save his life. However, the area they are traveling through has no hospital, few phones, and residents unwilling to help.
Ben hides out on an Indian reservation from Fletcher. He finds himself in the middle of a "generation gap" argument between a grandfather who is interested in maintaining tribal traditions and a rebellious grandson who is more interested in the "white guy"'s money. Fletcher plays on the youth's desire for money, but when he refuses to turn Ben over, Fletcher and his cohorts raid the reservation.