A crew of astronauts on the Ares III mission to Mars is forced to evacuate their landing site in Acidalia Planitia due to an intense sandstorm. During the evacuation, botanist and engineer Mark Watney is struck by debris and lost in the storm. The crew, unable to locate him and believing him to be dead due to his suit's biomonitor being damaged, makes the difficult decision to leave the planet to preserve their own lives. However, Watney survives the storm and regains consciousness to find himself alone on the hostile surface of Mars, with no way to communicate with Earth.

Watney, using his ingenuity and resourcefulness, sets out to survive on the limited supplies left at the Hab, the Mars base, until the next scheduled Mars mission lands in four years. Knowing that he must ration his food, he creates a makeshift farm inside the Hab using Mars soil fertilized with human waste and water produced by burning hydrogen from leftover rocket fuel. Watney modifies the habitat's equipment to generate water and begins growing potatoes, stretching his food supply. Meanwhile, he scavenges parts from previous missions to rebuild his communication equipment. Back on Earth, NASA discovers that Watney is alive and engineers a daring and risky plan to rescue him, even as the world eagerly watches the fight for survival unfolding millions of miles away.