One luxury retreat. Nine perfect strangers. Ten days. What could possibly go wrong? Luxury health and wellness retreat Tranquilium House promises rest and relaxation – exactly what these nine strangers are looking for. Miles from anywhere, they have no way to reach the outside world. Just time to think about themselves, and get to know each other. But the resort director has something else in mind. A very different, and very dark, agenda. These nine strangers have no idea what’s about to hit them.