Brooks Wilson (George Segal), a frustrated commercial artist, is torn between his wife, Selma (Eva Marie Saint), with whom he has two children, and his mistress, Grace (Janis Young), who is interested in a long-term relationship. Brooks' life begins to quickly unravel when he and Selma attend an exclusive party where he's hoping to impress a powerful businessman, Lepridon (Sterling Hayden), who is on the verge of offering him a lucrative commission.