In a California desert town, a short-order cook with clairvoyant abilities encounters a mysterious man with a link to dark, threatening forces.

Gunslinger Jonah Hex is appointed by President Ulysses Grant to track down terrorist Quentin Turnbull, a former Confederate officer determined on unleashing hell on earth. Jonah not only secures freedom by accepting this task, he also gets revenge on the man who slayed his wife and child.

When an asteroid threatens to collide with Earth, NASA honcho Dan Truman determines the only way to stop it is to drill into its surface and detonate a nuclear bomb. This leads him to renowned driller Harry Stamper, who agrees to helm the dangerous space mission provided he can bring along his own hotshot crew. Among them is the cocksure A.J. who Harry thinks isn't good enough for his daughter, until the mission proves otherwise.

When vengeful General Francis X. Hummel seizes control of Alcatraz Island and threatens to launch missiles loaded with deadly chemical weapons into San Francisco, only a young FBI chemical weapons expert and notorious Federal prisoner have the stills to penetrate the impregnable island fortress and take him down.