‘This is a film about a runaway train.’ The previous sentence is true, but it completely fails to capture the essential magnificence of Unstoppable so we’re going to try another sentence. ‘This is a film directed by Tony ‘Top Gun’ Scott in which Malcolm X and James T Kirk have to drive a train 80mph – in reverse – in order to chase down a half-mile long locomotive missile before it mashes an entire city.’ Yeah, that’s more like it.