Following the death of her husband, Sir Florian, beautiful Lizzie Eustace mysteriously comes into possession of a hugely expensive diamond necklace. She maintains it was a gift from her husband, but the Eustace lawyers insist she give it up, and while her cousin Frank takes her side, her new lover, Lord Fawn, declares that he will only marry her if the necklace is surrendered. As gossip and scandal intensify, Lizzie’s truthfulness is thrown into doubt, and, in her desire to keep the jewels, she is driven to increasingly desperate acts.