A man is involved in a car accident on a dark, foggy night, but is saved by an elderly stranger who is struck by the vehicle instead. The man is later handed an envelope by a police officer that was found in the pocket of the deceased, which contains a note with the words 'Study Physics'. He follows this advice and becomes a celebrated physics professor, eventually inventing the world's first time machine. He then uses the machine to travel back to that fateful night to save his younger self, resulting in his own death.