A 70-mile-wide asteroid is en route to Earth, and the last best attempt to counter it has failed. Also failing is the marriage of soft-spoken insurance salesman Dodge; the breaking news that the world will end in an estimated 21 days cues his wife to leave him on the spot.
Dodge is a man who has always played by the rules of life, while his neighbor Penny is an extroverted woman who hasn't. When a riot breaks out around their apartment building, Dodge realizes that he must seek his wife out before it's too late while Penny makes the decision to spend her last days with family in England.
On the road together, the unlikely traveling companions' respective personal journeys accelerate, and their outlooks - if not the world's - brighten.