A Midsummer Night's Sin. The Blackthorn Brothers, #2

Book Two of The Blackthorn Brothers Series. Robin "Puck" Blackthorn is young, rich, handsome as sin, and delights in the life he lives. A single stolen kiss at a masquerade ball should be nothing more than a lark, but that explosive embrace has unexpected consequences when he is suddenly thrust into helping a beautiful damsel in distress. Regina Hackett hadn't wanted to attend the masquerade with her cousin.
When that cousin disappears, she turns to Puck for help, only to realize they've stumbled onto a dark and dangerous secret that threatens not only her cousin, but Regina's entire world. As the two embark on a dangerous journey through London's seamier side, Regina discovers that beneath Puck's lighthearted façade is a man willing to dare anything to protect her . and to convince her to take a chance on a future seemingly beyond their grasp.