Wealthy, middle-aged English squire Henry Maurier (Charles Boyer) has a bitter quarrel with his querulous, invalid wife Emily (Rachel Kempson), when he finds her giving a check to her no-account brother, Robert Lester (Hugh French). Henry tears up the check and orders Robert from the house, then turns to long-time friend and neighbor, Janet Spence (Jessica Tandy), to help him patch things up with Emily.

Janet, who has spent most of her life caring for her arthritic father, General Spence (Cecil Humphreys), agrees, but finds that Emily is bitterly cynical about Henry. Janet also talks with Emily's nurse, the man-hating Caroline Braddock (Mildred Natwick), who is contemptuous of Henry's insensitivity toward Emily.

Later that evening at a club, Henry meets young Doris Mead (Ann Blyth), whom he has secretly been romancing for some months, then runs into Robert, who promptly demands money to remain silent. When Henry returns home that night, family physician James Libbard (Cedric Hardwicke) informs him that Emily has died, apparently of a heart attack. Janet is shocked when Henry immediately takes a trip after Emily's death.

Upon his return, Janet meets Henry at his home during a violent thunderstorm and when the power goes out, gains the courage to confess she has been in love with him for years. Embarrassed, Henry admits he has married Doris while away and Janet pretends her revelation was only a joke.

Later, when Nurse Braddock, angered over Henry giving Doris a broach meant for her, tells Janet she believes Henry murdered Emily, Janet encourages her to report her suspicions to the police. Henry and Doris are called back from their honeymoon and Emily's body is exhumed for an autopsy, which confirms that she was indeed poisoned by arsenic.

At the subsequent inquest, Henry's relationship with Doris before Emily's death is revealed, as is Doris' pregnancy and the fact that on the day of Emily's death, Henry purchased a weed killer laced with arsenic. In a moment of guilt and doubt, Doris attempts suicide, but is saved by Dr. Libbard, who believes Henry is innocent. Henry is bound over for trial, found guilty and sentenced to be hanged.

Dr. Libbard notices Janet's increasing strain during and after the trial, and she admits to being plagued by insomnia. Just before the execution, Janet visits Henry in prison and coldly reveals that she murdered Emily hoping he would then marry her. Henry tries to have this reported to the authorities, in vain. The night of the execution, Dr. Libbard, in an attempt to force a confession from Janet, sets the clock forward an hour, and as the time of execution approaches, she breaks down and ultimately confesses in exchange for medication that allows her to sleep. Dr. Libbard telephones the authorities and stops Henry's execution in time.

A 1948 American film-noir drama mystery film produced & directed by Zoltán Korda, screenplay by Aldous Huxley, based on his 1922 novelette "The Gioconda Smile", cinematography by Russell Metty, starring Charles Boyer, Ann Blyth, Jessica Tandy, Cedric Hardwicke, Mildred Natwick, Cecil Humphreys, Hugh French, Rachel Kempson, Carl Harbord, John Williams, Leyland Hodgson, Ola Lorraine, Harry Cording, Lydia Bilbrook, Boyd Irwin, Alec Harford, Wilton Graff, Wilson Benge, Reginald Sheffield, Patrick Aherne, Colin Kenny, Holmes Herbert, Eric Wilton, Marjorie Eaton, Leslie Denison, Mari Aldon, Vernon Downing, and Frederick Worlock. Screen debut appearance of Valerie Cardew. Final screen appearance of Elizabeth Valentine. Released by Universal Pictures.

Jessica Tandy, fresh from her Broadway role as the original Blanche du Bois in "A Streetcar Named Desire" in the same year. gives the greatest performance of her film career. Tandy was unfortunately relegated to secondary roles for the rest of her career until she won an academy award near the end of her life for "Driving Miss Daisy" (1989).

Hungarian-born Zoltán Korda, of the illustrious film family (brother Alexander), directed this (his) masterpiece.

Henry Maurier quotes from Wordsworth's "Ode to Duty" (1807): "Stern daughter of the Voice of God". Nurse Braddock quotes from Romans II:xix: "Vengeance is mine, saith The Lord".

This was presented on Lux Radio Theatre March 22, 1948. Boyer and Blyth reprised their original roles in the adaptation. "Theater Guild on the Air" broadcast a 60 minute radio adaptation of the movie on March 13, 1949 with Charles Boyer reprising his film role.

This thoughtful, exciting, romantic film-noir provides some interesting character studies by Aldous Huxley in his brilliant, exceptionally intelligent, and literate tale of country-house frustration and murder. Huxley's less interested in the logistics of murder than its psychology. Great Cast, great dialogue, one of Jessica Tandy's best! A very well written Hollywood production so skillfully put together that its multi-national cast needs no cumbersome explication. This is a real gem, exciting from start to finish.