Mark Watney (Matt Damon) is a very smart man in a very bad situation. A member of a manned mission to Mars, he was struck by a piece of debris during a storm which separated him from the rest of his crew. Believing that Watney had been killed, and faced with the agonising choice between leaving him or being stranded themselves, his crew left and started their long, mournful journey back to Earth. Fortunately, Watney survived. Unfortunately, he's alone on Mars with limited supplies, no way of contacting his crew or NASA, and no means of escape. Faced with the prospect of a long stay on a dead planet, with eventual starvation the most likely outcome, Watney would be forgiven for giving in to despair. Instead, he becomes a regular Robinson Crusoe on Mars (though not the actual Robinson Crusoe on Mars) and uses the tools at hand and his scientific know-how to try and survive, no matter how much the odds are stacked against him.