'A pure action horror movie set-up, a life-or-death moral dilemma and a terrific, devious twist... I could hardly look away' GILLY MACMILLAN, AUTHOR OF THE BURNING LIBRARYOne week to escapeHigh in the mountains, a sudden rockslide traps ten hikers in an abandoned bunker, nicknamed 'The Ark'. Then it starts to flood.One person will be sacrificedThere is only one chance of survival - in order for the rest of them to escape, someone must be left behind.But one of them has other plansAs they struggle to decide who to abandon, the group is torn apart by a brutal murder. And it won't be the last.Can they unmask the murderer and reach safety before the water rises? Or will The Ark become their tomb?