Guilty Wives by James Patterson & David Ellis

Only minutes after Abbie Elliot and her three best friends step off of a private helicopter, they enter the most luxurious, sumptuous, sensually pampering hotel they have ever been to. Their presidential suite overlooks Monte Carlo, and they surrender: to the sun and pool, to the sashimi and sake, to the Bruno Paillard champagne. As the weekend moves into pulsating discos, high-stakes casinos, and beyond, Abbie is transported to the greatest pleasure and release she has ever known.
 
In the morning's harsh light, Abbie awakens on a yacht, surrounded by police. Something awful has happened: something impossible, unthinkable. Abbie, Winnie, Serena, and Bryah are arrested and accused of the foulest crime imaginable.
 
And now the vacation of a lifetime becomes the fight of a lifetime—a fight for survival. Guilty Wives is the ultimate indulgence, the kind of nonstop joy-ride of excess, friendship, betrayal, and danger that only James Patterson can create.