In Midnight Lace, Doris Day's character, Kit Preston, is a rich American living in London with her husband, Tony Preston (played by Rex Harrison). When Kit begins to receive threatening phone calls, she becomes increasingly frightened and paranoid.
Despite her pleas for help, nobody takes her seriously, including her husband and the police. When the anonymous caller begins to make threats in person, Kit's mental state continues to deteriorate.
As the plot unfolds, it becomes evident that the threats are not what they seem and that there may be more to Kit's situation than meets the eye. The film builds to a tense and dramatic climax, revealing the truth behind the mysterious phone calls and Kit's apparent madness.
Featuring a strong supporting cast, including John Gavin, Myrna Loy, and Roddy McDowall, Midnight Lace is a gripping thriller that keeps audiences on the edge of their seats until the very end.