Three Days of the Condor (1975)

A man named Turner works for the CIA reading books and postulating possible scenarios that could be applied to inteliigence work. He goes out to get lunch but when he returns everyone at the center has been killed. He calls his superior and asks for someone to bring him in, he tells him that his section chief will get him but when he arrives, the man tries to shoot him, he manages to shoot back and escape. In an act of desparation, the abducts a woman and forces her to shelter him until he can figure out what is going on. When someone goes to the woman's house and tries to kill him, he kills the man and discovers that he has a connection to the CIA, which means that someone in the CIA is behind the attempt on him.