The basis for the film, the one we'll be following the most throughout the 130-minute run time, is of course that of Matt Damon's Mark Watney; he is the Martian. It'll go from his crash-landing and discovery that he has somehow managed to survive, to trying to figure out just how to keep things that way. However, while he'll provide the meat of the story, and is the axis around which everything else revolves, this isn't going to be just two-hours of Damon being the best damn botanist on Mars. There will be two other teams we follow: the Ares 3 crew who are in space, set for a return to Earth, and the NASA officials back on the ground. The crew will provide plenty of the emotion to the story, as they first come to terms with leaving the crewmate for dead, and then the realisation that they've actually left him stranded alive on Mars. Back home, there will be a lot of political tension and drama as the NASA officials deal with the fallout of Watney's death, the reveal that he's still alive, and all of the various implications of whether or not they should, and indeed could, rescue him. If it's done like the book, this structure means we'll be following the three different stories across the movie, all interlinked by the desperate need for Watney's survival, and each should offer their own interesting and unique perspective, meaning that the story won't start to flag.