THEY THOUGHT THEY WERE SAFE . . . The Sanctum is a luxurious, self-sustaining survival condominium situated underground. It's a plush bolt-hole for the rich and paranoid - a place where they can wait out the apocalypse in style. When a devastating super-flu virus hits, several families race to reach The Sanctum. All have their own motivations for entering. All are hiding secrets. But when the door locks and someone dies, they realize the greatest threat to their survival may not be above ground - it may already be inside . . .Under Ground is a page-turning locked-room mystery from the combined talents of Sarah Lotz and Louis Greenberg, writing as S. L. Grey. It is perfect for fans of Under the Dome by Stephen King and films such as The Hole and The Descent (with a pinch of And Then There Were None by Agatha Christie).