Beatrice Lockwood, one of the intrepid ladies of Lantern Street, is in the middle of a case when her past comes back to haunt her. A former spy for the Crown has come out of retirement - after a disastrous case that left him scarred and needing a cane - to hunt down his sister's blackmailer. Beatrice is his chief suspect. But when he realizes that she is not the villain he seeks, they set out to find the real extortionist together.