A human heart floats in a toilet. It's a shocking image that helps director Stephen Frears and screenwriter Steven Knight lay out the plight of illegal immigrants in London. Okwe (Chiwetel Ejiofor), a doctor in Nigeria, now toils as a cabbie and hotel clerk. He is befriended by Senay (Audrey Tautou), a Turkish maid. Both are exploited by Juan (Sergi Lopez), the hotel manager, who traffics in human organs. Fueled by gripping suspense, dark humor and outraged humanity, the film is a modern horror story that means to shake you, and does.