Horror film icon James Whale directed this well-detailed thriller about a man questioning his wife's honesty after a friend begins to doubt his own. Dr. Paul Held (Frank Morgan) is an attorney who has been asked to come to the aid of his old friend Walter Bernsdorf (Paul Lukas); Bernsdorf has been accused of killing his wife, and he wants Held to defend him in court. Bernsdorf admits to shooting his spouse, but he tells Held that he lost control when he found out his wife was having an affair. Held takes on his friend's case, but as he pours over the facts in the Bernsdorf slaying, he finds himself wondering about the fidelity of his own wife, Maria (Nancy Carroll) -- and begins to seethe with jealousy when he find that she has indeed been sleeping with another man. A Kiss Before The Mirror also features actress Gloria Stuart; James Whale would remake the same story six years later, under the title Wives Under Suspicioun.
by Mark Deming synopsis