A decade after solar flares tore apart the ozone layer, turning Earth into a barely liveable irradiated hothouse, engineer Finch Weinberg (Tom Hanks) ekes out a living in his St. Louis laboratory, his only companions his dog, Goodyear, and a cute little helper robot he’s cobbled together named Dewey. It’s clear that Finch hasn’t clapped eyes on another human in years, although he’s a self-sufficient fixer who has made a comfortable if lonely life for himself.
But Finch is dying, and he knows that looking after Goodyear is well beyond Dewey’s programming, and so he builds a humanoid robot with the aim of teaching it how to care for the mutt after he has passed on. However, an approaching mega-storm that will pretty much wipe St. Louis off the map has stepped up the timetable. Finch, Dewey, Goodyear, and the robot, who will eventually name himself Jeff (Caleb Landry Jones in mocap) pile into Finch’s heavily modified RV and head off for San Francisco, where they might just be safe, and on the way, Finch tries to teach Jeff about life, the universe, and the proper care of canis domesticus.