One of us will be dead by morning / David Moody.

"The first in a new series from Hater author David Moody, One of Us Will Be Dead by Morning is brimming with horror. Fifteen people are trapped on Skek, a barren island in the middle of the North Sea somewhere between the coasts of the UK and Denmark. Over the years this place has served many purposes--a fishing settlement, a military outpost, a scientific base--but one by one its inhabitants have abandoned its inhospitable shores. Today it's home to Hazleton Adventure Experiences, an extreme sports company specializing in corporate team building events. Life there is fragile and tough. One slip is all it takes. A momentary lapse leads to a tragic accident, but when the body count quickly starts to rise, questions are inevitably asked. Are the deaths coincidental, or something else entirely? Those people you thought you knew well, can you really trust them? Are you standing next to a killer, and will you be their next victim? A horrific discovery changes everything for everyone. There's no way home now, and a trickle of rumors becomes a tsunami of fear. Is this really the beginning of the end of everything, or a situation constructed by the mass hysteria of a handful of desperate and terrified people? The lower the population, the higher the stakes. Kill the rest of them, before one of them kills you"--