The Lion's Den by Katherine St. John

Sex, betrayal, and intrigue: A dream vacation on a luxurious yacht turns deadly in this pulse-pounding beach read "chock full of delicious characters who flaunt their sins . . . like the latest Birkin bag" (Adriana Trigiani).
 
Belle likes to think herself immune to the dizzying effects of fabulous wealth. But when her best friend, Summer, invites her on a glamorous getaway to the Mediterranean aboard her billionaire boyfriend's yacht, the only sensible answer is yes. Belle hopes the trip will be a much-needed break from her stalled acting career and uniquely humiliating waitressing job, but once she's aboard the luxurious Lion's Den, it soon becomes clear this jet-setting holiday is not as advertised.

Belle's dream vacation quickly devolves into a nightmare as she and the handful of other girls Summer invited are treated more like prisoners than guests by their controlling host—and in one terrifying moment, Belle comes to see Summer for who she truly is: a vicious gold digger who will stop at nothing to get what she wants.

Belle realizes she's going to have to keep her wits about her—and her own big secret closely hidden—if she wants to make it off the yacht alive.
 
Includes a Reading Group Guide, exclusive epilogue, and sneak peak of Katherine St. John's next book, The Siren.