In the spring of 1817, I agree to track down the missing necklace of a society matron and prove the innocence of her maid, who has been arrested for the theft. The matron in question declares that the rival for her husband's affections has stolen the necklace, but I soon realize that the problem is not so simple. I recruit Lady Breckenridge to infiltrate the household, while Lucius Grenville and I, assisted by Grenville's robust footmen, follow other leads.The investigation soon unearths scandal and past secrets, and I find myself once more competing with the underworld criminal James Denis as I scramble to locate the necklace and clear all parties before an innocent hangs for the crime.The events in this novella occur between the end of The Sudbury School Murders and the beginning of A Body in Berkeley Square.