Rami Bahrani draws on the myth of Sysyphus – who was condemned to perpetually push a boulder up a hill, only for it to roll back down again – for this bleak look at the life of a Pakistani immigrant in the Land of The Free.

Like many films before and since, it holds the concept of the American Dream up to the harsh light of reality, showing that, for many, finding time to sleep is a problem, let alone time to dream. This is a tale of days that are simultaneously full and empty, hidden pasts and unseen histories.

Ahmad (Ahmad Ravzi) is the man pushing the cart of the title. Starting his day at 3am, to push his cart – he can’t afford a car to pull it – to his corner, where he sells bagels and coffee all day, while hawking DVDs and doing anything else he can to make ends meet by night.

“How long have you been here?” a fellow ex-pat asks. “Too long,” he replies.

As with many indie films, appearances are deceptive. Ahmad looks like just another immigrant vendor but, in fact, he was a rock star in Pakistan. Now in the US of A, he has lost his wife, his son and – for the most part – any sense of personal worth.

And yet, he goes on, pushing – or rather being pushed by – his cart, driven to try to climb the greasy pole to cart ownership, get back his son, achieve something – anything - even as he senses the futility of what he is doing. There are other characters here, too, a Spanish girl who he may be falling in love with and another Pakistani who has made his way to the New York middle-class.

Although the acting isn’t so hot from the non-professional bit part players, Ahmad Ravzi – also a non-professional actor and former push cart seller himself – puts in a stoic and solid performance. And while the cinematography isn’t great, Bahrani’s camera focuses on the city’s underclass well. But, since this film is unremittingly grim it keeps you at arm’s length.

Given that Ahmad is our focus, too many details of his life remain in the shadows, making it hard to strike up a proper rapport with him. You sense Bahrani missed the opportunity to let us in a little more, so that we could empathise with his plight instead of just thinking, poor old thing. That said, this is a brave document about those whose daily struggle goes unheeded by the rest of us.