Larry Kozinski (Danson) and Maria Hardy (Rossellini) meet at the marriage of Larry's uncle Phil and Maria's mother Edie (Aleandro). Newly made cousins-by-marriage, they find they have more in common than expected as their respective spouses, insecure Tish (Young) and boorish Tom (Petersen) begin an affair. Over a series of ritualized family events, dreamer Larry and repressed Maria decide to exact revenge on their spouses by pretending to have an affair themselves. Their good-natured plan takes on unexpected gravity when they learn not only are they great friends, but they realize they're falling in love with each other.