Due to financial hardships at Tawcester Towers, the Dowager Duchess has decreed that the only way the family fortunes can be restored is to marry Blotto off - to an American! The aristocratic sleuthing siblings end up being transported across the Pond to the gangster-ridden hell-hole that is Prohibition Chicago.
This book is part of the Blotto and Twinks Books series and is book #4 in the series.