A Season for Treason (Deception and Discipline Book 1)

This wallflower doesn't mind that no one notices her, she's using it to spy on the ton and catch a traitor to the Crown. Everyone overlooks her...until one night when she sneaks into the Society of Sin's debaucherous gathering. Rex, the rakish leader of the Society, catches the interloper and demands she pay a penance for trespassing.