Wealthy, brilliant, and meticulous Ted Crawford, a structural engineer in Los Angeles, shoots his wife and entraps her lover. He signs a confession; at the arraignment, he asserts his rights to represent himself and asks the court to move immediately to trial. The prosecutor is Willy Beachum, a hotshot who's soon to join a fancy civil-law firm, told by everyone it's an open and shut case. Crawford sees Beachum's weakness, the hairline fracture of his character: Willy's a winner. The engineer sets in motion a clockwork crime with all the objects moving in ways he predicts.

Ted Crawford shoots his unfaithful wife, confesses to the police - orally and in writing - but then pleads not guilty and opts to defend himself in court. The young DA assigned to the case, Willy Beachum, has had a successful career with a 97% conviction rate. Beachum however is actually on his way to a lucrative position in a big private law firm, but his desire to win keeps him on the case. What ensues is a battle of wits between the two as Crawford systematically destroys his opponents case.