Secrets Of The Heart by Candace Camp

On the eve of her wedding to Michael Trent, the Earl of Westhampton, Rachel Aincourt tried to elope with another man–only to be unceremoniously returned to her fiancé by her strong-willed father. Burdened by guilt and shame, Rachel felt she'd gotten what she deserved: a loveless marriage to a cold, enigmatic husband. She was wrong.

Behind Michael's proper demeanor lay a man who thrived on danger and intrigue–and now he'd been drawn into one of Bow Street's toughest cases. When the crime turned into a murder that involved Rachel, Michael found a new way to employ his mastery of disguise: seducing the wife he secretly loved. But would he finally be able to win her heart…or would he destroy his last chance for happiness?