Mark Bellison (Ricky Gervais) lives in a world just like our own, but no one lies there. Everyone is completely honest all the time. The first half of the movie shows Mark's sad life a struggling loser, and how he is insulted by his completely honest coworkers, his Mom, and Anna (Jennifer Garner), his date. His Mom gets sick, and he makes up a story about an afterlife to help comfort his Mom on her deathbed. Doctors and nurses overhear him, and soon Mark becomes an international authority on the afterlife. People camp on his lawn to learn more. Mark develops a story about the "Man in the Sky," who functions like God, and he pastes his theology on two pizza boxes like Moses and the ten commandments. Mark learns to lie to help his friends, get money at the bank, cheat at the casino, and eventually to win the affection of Anna.