<p><strong>All of them are friends. One of them is a killer.</strong></p><p>During the languid days of the Christmas break, a group of thirtysomething friends from Oxford meet to welcome in the New Year together, a tradition they began as students ten years ago. For this vacation, they've chosen an idyllic and isolated estate in the Scottish Highlands--the perfect place to get away and unwind by themselves.</p><p>They arrive on December 30, just before a historic blizzard seals the lodge off from the outside world.</p><p>Two days later, on New Year's Day, one of them is dead.</p><p>The trip began innocently enough: admiration of the stunning, if foreboding, scenery; champagne in front of a crackling fire; and reminiscences about the past. But after a decade, the weight of secret resentments has grown too heavy for the group's tenuous nostalgia to bear. Amid the boisterous revelry of New Year's Eve, the cord holding them together snaps.</p><p>Now one of them is dead . . . and another one of them did it.</p><p>Keep your friends close, the old adage goes. But just how close is too close?</p>