ObscureHollywood.net’s review published on Letterboxd :
The death of his self-centered, invalid wife frees Charles Boyer to marry his young mistress (Ann Blyth). The sudden marriage astounds neighbor Jessica Tandy who thought that widower Boyer would marry her. Due to the suspicions of the wife’s nurse, Mildred Natwick, the police exhume the body. The wife was poisoned. Despite his protestations of innocence, Boyer is tried, convicted, and sentenced to death. The family doctor, Sir Cedric Hardwick, knows who is actually guilty, but can he obtain a confession in time?
The title reveals a central theme of the plot. Another theme is an old one, “murder will out”.