State troopers investigate footprints leading from a mysterious crash site to a diner, where a group of passengers from a bus trip are waiting out a snowstorm. The only patrons of the roadside eatery are the bus passengers, but there is one more diner than there were people on the bus. Suspicion grows among the stranded travellers as they try to guess which one of them is from the alleged UFO. Who is the real Martian? The intergalactic twist provides the classic Twilight Zone surprise ending.