As the end of the world approaches, mysterious ads begin to appear everywhere, thanking Chuck for 39 wonderful years of service. Marty Anderson (Chiwetel Ejiofor), a man who had imagined the end times very differently, becomes fascinated by one question: who is this Chuck, and why does it seem as if the fate of the world is tied to him? Slowly but surely, memories, personal tragedies, and cosmic mysteries intertwine into an emotional story about life, loss, and the impact one person can have — even if no one fully understands why.