Impetuous

Carlie, a diligent teacher, is dragged to a costume party in a daring outfit her friend made her wear. At the party, she is persistently pursued by Tyler, a known playboy. Tyler is her friend’s brother-in-law, but he doesn’t realize that it’s actually "boring old Carlie" under the mask. Knowing she’d normally never have a chance with a guy like him, Carlie happily allows herself to be seduced. The next morning, Carlie leaves without revealing her identity and Tyler becomes determined to find the woman in the mask! Source: Harlequin