As a master of disguise, Thomasina Wynchester can be a polite young lady—or a bawdy old man. Anything to solve the case. Her latest assignment unveils a top-secret military cipher covering up an enigma that goes back centuries. But when Tommy’s beautiful new client turns out to be the highborn lady she’s secretly smitten with, more than her mission is at stake...

Bluestocking Miss Philippa York doesn’t believe in love. Her cold heart didn't pitter-patter when she was betrothed to a duke, nor did it break when he married someone else. All Philippa desires is to rescue her priceless manuscript and decode its clues to unmask a villain. She hates that she needs a man's help—so she’s delighted to discover the clever, charming baron at her side is in fact a woman. Her cold heart... did it just pitter-patter?