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.
A newspaper society page carries the news that Ben's one-time fiancee, Sylvia Cartwright, is about to be married. She does not love the man she's about to wed, but is instead taking the step in hopes of getting Fletcher to leave her alone. Fletcher is certain that Ben will not allow the wedding to pass without seeing Sylvia once again, so he surrounds the groom's home on the day of an engagement party.
A salvage dealer carrying leaking World War I gas canisters offers Ben a ride to escape from Fletcher. In order to help his son he needs to sell the canisters, but the only place that will buy them is owned by Arthur Maitland -- and they won't buy unless the man tells Fletcher where Ben is hiding.
Ben is interested in the work of Dr. Walter Koster, who is studying a link between blood hemoglobin and aging. Ben goes to work in the clinic where Dr. Koster is doing his research and explains his blood to the doctor in hopes that Dr. Koster can synthetically re-create it. Dr. Koster's experiments, however, fail. Worse, Maitland convinces Koster to hand Ben over to him in exchange for a foundation grant.
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.
Two computer programmers have a vested interest in Ben. Duane sees him as a $1,000 a day payment from Maitland, since the computer program he designed allows Fletcher to get one step ahead of Ben and trap him in a small town. Duane's finacee, Terry, has a more personal interest in Ben: his blood can save her young daughter's life, if only she can help Ben escape by running contrary to what the computer predicts he will do.
A sheriff is shot in a dispute over pay. Ben, friends with the men who shot the lawman, is implicated by the vengeance-seeking deputy, who organizes an "honor posse" to hunt Ben down. Cornered and facing a charge of murder, Ben is faced with the unpleasant choice of surrendering to the bloodthirsty posse or going with Fletcher.
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 shot while hiding out in Mexico. A fellow American helps Ben sneak back into the U.S. as part of a group of workers to be hired for farm work. The two end up on a tomato farm run by a ruthless farm foreman who is using a banned pesticide in order to get a good crop and wrest control of the farm from the widowed owner.
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.
A lead on Jason brings Ben to a costal community. The only road to the town is blocked by a chain and a sign that says, "Keep Out -- This Means YOU." When Ben ignores the sign he discovers unfriendly townspeople and a grave with the name "Jason Richards" on the headstone. Ben's investigation shows that the deceased is not his brother...but also shows that the man may have been murdered.
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.
Ben has found a man named Jason Richards. The man also grew up in an orphanage, but he cannot remember the details due to a head injury. Unfortunately, Fletcher has also found the man and offers him $20,000 to spend six months at the National Research Institute. Jason desperately needs the money, but what if he truly is Ben's brother and has the same unique blood?