This Edgar Wallace mystery takes place in London. Hope Joyner, ward of a Mr. Hallet whom she has never met, is in love with Sir Richard Hallowell. Diana Montague, who was once engaged to Sir Richard, now keeps very dubious company Sir Richards brother Graham for one. He has just been released from prison. Since Graham has been away Diana has acquired money, and she is now Press Secretary for the Prince of Kishlastan, who according to Colly Warrington, is totally besotted with her... About an attempt to steal the British crown Jewels, Edgar Wallace has woven a story that is distinctly superior to the general run of mystery yarns.