Ten years have passed since a solar flare destroyed the ozone layer, increasing temperatures to 1100 degrees Fahrenheit (70 degrees Celsius) and turning the planet Earth into a largely-uninhabitable wasteland scorched by ultraviolet radiation, and subject to extreme weather events. One of the few survivors, robotics engineer Finch Weinberg, lives alone with his dog Goodyear and a helper-robot Dewey 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 with a heat and ultraviolet-resistant protective suit.
Dying of an undisclosed ailment, 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.)
When a massive storm approaches St. Louis, and it is predicted to last 40 days, Finch, Jeff, Dewey, and Goodyear set out in a heavily modified motorhome towards San Francisco. Because of the hasty departure, only 72 percent of the data could be uploaded to Jeff, and has the mental capacity of a child. 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, and as Jeff shows more intiative, he inadvertently stumbles into a trap which destroys Dewey, and their motorhome is pursued by an unknown car. However Finch forgives Jeff after it helps their vehicle from being overtaken, in spite of a panicked error in judgment by Finch.