Summer 1890. Guy Clements, spoilt, rich and charming, has invited his friend Max Fareham to spend a month of hedonistic leisure at his London residence. Meanwhile below stairs, clever, streetwise Madeleine Peterson is hatching a scheme to lift herself out of domestic service and her brother Michael out of prostitution; and a few streets away, amateur spy Louis la Rothiere is gloating over his latest cache which may, just may, turn out to be the scoop of a lifetime. An apparently straightforward case of domestic pilfering is about to take an unexpected turn involving blackmail, mistaken identity, War Office doduments and the Love That Dare Not Speak Its Name - and for once, Sherlock Holmes and Dr Watson find themselves repeatedly and hilariously wrong-footed.