“I am a rock,” sang Paul Simon, “I am an island.” In climber Aron Ralston’s case, it was a rock that did for his pretence of being an island.Ralston (a supremely convincing James Franco) is the self-involved adrenaline junkie who, in 2003, having told no-one where he was going, spent five days trapped under a boulder in Utah, before freeing himself in extraordinary circumstances. If there’s any spoiler here, it’s not that he gets out—the film is based on the book he wrote about the ordeal—so much as how he managed it.