Hitchcock used cars a lot in his movies to wind up the story tension. The main character in Psycho steals money from a bank and drives through the desert on the way to the Bates motel. By the time she gets out of the car, the story has barely begun but we are already nervous for her and can imagine it will turn out badly.
"Locke" is the story of a British engineer who specializes in concrete - driving his car for eighty minutes. In the beginning, very briefly, we see his current project - a skyscraper construction site, and from then on it's all a single character in his BMW. His name is Ivan Locke, played by Tom Hardy. He speaks on his hands-free cell to family, colleagues and one other very important person for the entirety of the film. He speaks to his dead father as an empty seat in the rear-view. He speaks to the movie audience through expressions, gestures, gulps of cough medicine. No radio. No flashbacks. No crashes, no chases, nothing that makes you hold your breath except for cell conversations that range from frantic to comical. Then Locke's reaction to one desperate and emotional voicemail which I think is as good as you'll ever see in a movie performance.
Ivan Locke has made a decision. He must do one thing in the next few hours - be in one certain place and this will put at risk everything he has achieved in life. But it must happen. It must happen - to borrow a small riff from Hardy's chilling way of phrasing throughout the film. Millions of pounds currency and billions of future life events hinge on what happens with Locke's obligations to his employer. But he has made a human choice. And with an engineer's mind, he'll manage the rest.