Who could have predicted that the disappearance of the most ordinary maid from a Derbyshire estate would be the key to solving many seemingly unrelated dangerous and unusual crimes? Who would have imagined that the charming Emma Wallingford, a real lady, a talented mathematician and a born detective, would take on the investigation of this strange case? And who, in the end, could have considered it possible that Lord Derick Eivlin, who is in His Majesty’s secret service, busy searching for a traitor working for Napoleonic France, would passionately fall in love with a lady detective, and she would reciprocate the handsome intelligence officer? But what happened, it happened - and now the lovers must either win or perish... Derbyshire, June 1817 September, 1819, London, home of Lord and Lady Scarsdale