An illicit drug transforms a struggling writer (Bradley Cooper) from a man crippled by self-doubt on a downward spiral into a world-beater in Neil Burger’s latest thriller. Robert De Niro puts in one of his most impressive performances for years and, although the film has some problematical loose ends and the female roles are largely underwritten, this is a punchy and witty movie with a nice mix of action and intrigue. A flawed but entertaining sci-fi thriller.