For years, I remained stolidly baffled while all around, critics simpered and swooned at the words "Tom Hardy". The mere mention of his name caused hardened reviewers to whinny ecstatically as they slid to the floor. Well, it's time to do some swooning and simpering and whinnying and sliding of my own. Hardy gives us a masterclass in less-is-more acting for this absolutely engrossing, stripped-down solo piece, written and directed by Steven Knight, the screenwriter of Cronenberg's Eastern Promises and Frears's Dirty Pretty Things. For an hour and a half, all you see is Hardy himself, playing a construction manager at the wheel of his car, talking to the people in his life on his hands-free mobile – his boss, his wife, his former assistant. It's a story so involving, it sounds like someone came up to Knight in the pub, told him his life-story, and the director just scribbled it down on a couple of dozen beermats. Hardy plays Ivan Locke: a dependable, professional bloke who is about to supervise the pouring of thousands of tonnes of cement into the foundations of a new building in the midlands. But on the eve of the job, he abandons the site and drives south to London. Something momentous is happening, for which he is prepared to sacrifice everything in his life. Tom Hardy brilliantly suggests a guy with no experience of expressing his emotions, keeping it calm, holding it together, having the necessary phone conversations while the tears start trickling down his face. He looks like an Easter Island statue having a breakdown. At first I thought this might be a glorified radio play. Not a bit of it. You need to keep watching Hardy's face.