Michael Jennings (Affleck) is a reverse engineer who routinely has his recent memories erased after working on sensitive high-tech projects. He is often helped by his friend Shorty (Giamatti). He agrees to take on a project for James Rethrick (Eckhart), his old college roommate and close personal friend; Rethrick is CEO of Allcom. All Jennings is told is that he is to design something for three years in exchange for Allcom shares which will be worth a minimum of 10 million dollars. He meets and falls in love with Dr. Rachel Porter (Thurman), an Allcom biologist. However, after working for three years on the secret project, he wakes up with his memory erased and learns that he signed away his shares in Allcom which are worth 92 million dollars, and is left only with an envelope.