The Accidental Mistress by Tracy Anne Warren

He will expose her masquerade, but she will expose his heart.

To escape an arranged marriage, spirited Lily Bainbridge has staged her own death, and, disguised as a boy, she fled to London and a life of freedom. Yet her plans to live masquerade as an independent widow are thwarted by an encounter with a powerful and dangerously attractive marquis who wants to make her his mistress. Lily is afraid that if she gives him her innocence, he'll steal her heart.

Having agreed to a marriage of convenience to honor his family duty, Ethan Andarton, the Marquis of Vessey, has no intention of abandoning his rakish ways. Then fate intervenes in the guise of an impetuous young lady -- a woman bold enough to scheme her way to London, who tempts him with her mystery and her sensuality. Kiss after kiss, caress after tender caress, Ethan vows to discover all of Lily's hidden secrets. For beneath the layers of her clever ruse lies a burning passion that will ignite a tempestuous love neither of them can deny.

This book is part of the "Mistress Trilogy" series.
Here are some other books from this series: