The story starts with the Ghost (Ewan McGregor) taking up a job as a ghost writer to write the biography of the Prime Minister, Adam Lang (Pierce Brosnan). The last ghost writer that took up this job has just recently been found dead on the beach. The previous ghost writer, Mike, has left an entire manuscript very badly written and the Ghost only has a few weeks to write a final draft. Yet oddly, the Ghost cannot remove the manuscript from a certain room in the Prime Minister's home in the US. It's always raining on the island in which the home is located, giving the story a darker atmosphere.
Soon, after the Ghost starts questioning the Prime Minister and his wife to include in the biography, he realises that the Prime Minister never wanted to become a politician. It was only until later that he left acting school and pursued this dream. But why?
Things don't add up. Why did Mike die after he met up with the Prime Minister's colleague? Why does the Prime Minister and his wife's story seem unlikely? Is the Ghost getting into more trouble than he bargained for?