Love the Maiden Lane series and this is one of the best. Alf is the latest Ghost of St Giles and the first woman though she spends all her time dressed as a boy. She's had a run-in with the Duke of Kyle before and when she rescues him from assassins, she steals a kiss. This starts an adventure and eventual romance between the two. 
 Hugh FitzRoy, Duke of Kyle is widowed with two young sons and is on a mission from the King to bring down the Lords of Chaos. He needs the 'boy' Alf's skills at espionage to get information on the evil Lords. 
 The story moves right along with never a dull moment. I'm never quite sure of romances between the nobility and the common people, but the romance between Alf and Hugh works because Hugh is baseborn and his mother was an actress. His relatives are butchers and so Hugh is not so high in the instep that he can't appreciate Alf for what she is. The secondary cast is great and I can't wait for the next book which I think will be the Duke of Dyemore's story with Lady Jordan. There's a great setup for it at the end of this book.