The Ghost Writer

When a successful British ghostwriter (Ewan McGregor) agrees to complete the memoirs of former British Prime Minister Adam Lang (Pierce Brosnan), his agent assures him it is the opportunity of a lifetime. But the project seems doomed from the start not least because his predecessor on the project, Lang's long-term aide, died in an apparent accident. The ghostwriter flies out to work on the project, in the middle of winter, at an oceanfront house in the fictional village of Old Haven (an allusion to Vineyard Haven) on Martha's Vineyard. But the day he arrives, a former British foreign minister named Rycart accuses Lang of authorizing the illegal seizure of suspected terrorists and handing them over for torture by the CIA a possible war crime. Lang faces the threat of prosecution by the International Criminal Court, unless he stays in the U.S. or goes to another country that does not recognize that court.The controversy brings reporters and protesters swarming to the security perimeter of the island home where Lang is staying with his wife, Ruth (Olivia Williams), and his personal assistant (and mistress), Amelia Bly (Kim Cattrall). As the ghostwriter works, he uncovers clues suggesting his predecessor may have stumbled on a dark secret concerning Lang and that somehow this information is hidden in the manuscript he left behind. During Lang's absence, the neglected Ruth sleeps with the writer. The writer also meets an old man (Eli Wallach) living locally, who tells him that there is no possible way the current could have taken the body of the dead writer from the ferry where he disappeared to the beach location where it was discovered. The old man also reveals that a woman saw flashlights on the beach the night the body was discovered, but later fell down her stairs and went into a coma.The next morning, the ghostwriter follows the GPS in the car of the previous writer, which leads him to the estate of Professor Paul Emmett (Tom Wilkinson), who also appears in college photographs with Lang which have been left behind by the previous ghost-writer. The ghostwriter can tell that Emmett is hiding something. As the writer leaves Emmett's estate, he is followed by a car, but eludes it. The writer boards the ferry, but then flees the boat as he sees the car that had followed him drive on board. He decides to spend the night on the mainland, and stays in a small motel and while there, finds information on the Internet that points to Paul Emmett as a CIA agent.The writer then contacts Rycart (Robert Pugh), whose phone number was among the effects of his predecessor, and who tells him that the previous writer had said that he had hidden information in the "beginning" of the book. The men cannot, however, find anything in the manuscript's early pages. Lang then calls and the writer is told by Rycart to go with Lang. The writer warns that Lang will be able to avoid Rycart no matter what he does. On the plane, the writer accuses Lang of being a CIA agent recruited by Emmett, but Lang derides his suggestion.Upon departing the aircraft, Lang is assassinated, apparently by an anti-war protestor who had lost a son. The apparent assassin is in turn shot by police. The writer is interviewed and US authorities take his passport so that he can stay and provide information. Despite Lang's death, the ghostwriter is asked to complete the book for posthumous publication.During the launch party for the book, while talking to Amelia, she corrects the "beginning" clue as "beginnings" and Amelia also tells him that Paul Emmett was Ruth's tutor when she was a Fulbright scholar. He realizes that the clues were hidden in the original manuscript at the beginning of each chapter. He underlines the words at the beginning of each chapter and reveals the message, "Lang's wife Ruth was recruited as a CIA agent by Professor Paul Emmett of Harvard University." Ruth Lang has shaped Lang's every political decision to benefit the United States as directed by the CIA. After passing a note to Ruth of his discovery, the ghostwriter leaves the party with the original manuscript in hand. As he crosses the street off-camera, a car accelerates in his direction, and sound effects and flying papers indicate that he has been hit.

Question: What does the ghostwriter stumble upon?
Answer: A dark secret concerning Lang