Alfred Hitchcock Presents: Apex (1962)

Synopsis
Wealthy Clara (Vivienne Segal) has trouble believing her much-younger husband, Claude (Mark Miller), when he declares that he is 100-percent faithful to her. Rather than express these doubts to Claude, Clara confides in her best friend, Margo (Patricia Breslin) -- little suspecting that Margo and Claude are lovers. The plot thickens when Margo, hoping to get her mitts on Clara's money, suggests to Claude that he eliminate his suspicious spouse...then grows impatient when Claude appears to lose his nerve. ~ Hal Erickson, All Movie Guide