If This Be Sin Myrna Loy, Roger Livesey 1949

Myrna Loy stars as Lady Brooke in this British drama about a woman who accompanies her sick husband to convalesce in Italy, leaving behind her lover (Richard Greene). After a poison pen letter arrives, warning the husband (Roger Livesey) about his wife, Loy has to think past and makes up a story that Greene is actually in love with their daughter (Peggy Cummins). But things take a turn for the worst when both the daughter and the lover arrive in Italy.