Trailer:

Fifteen years have passed since a massive solar flare destroyed the ozone layer, turning the planet Earth into a largely uninhabitable wasteland ravaged by extreme weather events while being scorched by the sun’s ultraviolet rays, increasing surface temperatures to 150 °F (66 °C; 339 K). One of the few survivors, robotics engineer Finch Weinberg, lives alone with his dog Goodyear and a helper-robot Dewey[2] in an underground St. Louis laboratory once owned by the company he worked for before the cataclysm. Finch only ventures outside to search for supplies wearing a protective suit.

Dying of an undisclosed ailment (although Finch is seen reading a book on radiation poisoning), Finch is working on creating a more advanced humanoid robot companion to take care of his dog once he is gone. Finch feeds it volumes of encyclopedic knowledge, including a manual for training and caring for dogs. However, Goodyear initially doesn’t trust the robot (which eventually chooses the name Jeff).

Finch discovers that a massive storm is approaching St. Louis that will certainly destroy the area and kill him. Finch, Jeff, Dewey, and Goodyear set out in a heavily modified motorhome towards San Francisco. Because of the hasty departure, Jeff could download only 72% of his encyclopedic data, and his mental capacity requires training. Despite his condition worsening, Finch tries to teach Jeff some valuable lessons about life and how to protect Goodyear. Jeff’s inquisitive behavior both amuses and frustrates Finch, but the robot slowly shows more initiative.

By the time they reach Denver, Finch becomes bedridden and Jeff decides to loot an abandoned hospital with Dewey. Dewey unwittingly gets crushed by a beartrap and Finch retrieves Jeff to escape the city, realizing that the area is a trap set up by other humans. Later in the evening, the motorhome is pursued by an unknown car (which evidently followed them from the hospital). Finch makes a panicked error in judgment and crashes their vehicle through an underpass with too little clearance, but Jeff is strong enough to squeeze it out of sight. Finch begins to give up hope that he will survive the journey and tells a story (in a flashback) about how he rescued Goodyear.

Approaching their destination, the UV radiation has dropped low enough for Finch to be able to step out into the sunshine without a protective suit. Ecstatic, Finch spends an afternoon outside with Jeff, teaching him how to play fetch with Goodyear before quietly dying. After cremating Finch in a funeral pyre, Jeff and Goodyear make their way to San Francisco. Although they find the city habitable but deserted, they find possible evidence of surviving humans at the Golden Gate Bridge and set out to find them.