In 1978, a young British couple embarked on the trip of a lifetime through remote Central America. Chris Farmer and Peta Frampton set out on an exhilarating backpacking adventure, but their dream soon turned into a chilling nightmare when they were brutally murdered and the trail for their killer goes cold. Four decades later, failed by law enforcement, their family take up the manhunt and begin the descent into an unknown world of online sleuthing, making a shocking discovery.

麦克（拉塞尔·托维 Russell Tovey 饰）和女友薇迪亚（艾波·罗丝·雷瓦 Amber Rose Revah 饰）喜滋滋地搬进新房，准备在这里迎接两人爱情的结晶，没想到，阁楼里的一具无名尸体令两人陷入了复杂而纠葛的案情之中。 　　没有人知道这具尸体的身份为何，亦没有人知道她究竟为何会在此，探长莱恩（大卫·斯瑞弗 David Threlfall 饰）退休在即，宝刀未老的他接下了这个扑朔迷离的案子。没有线索，没有动机，没有现场，莱恩该如何拨开这重重迷雾，找到真相？随着调查的深入，莱恩意外发现了隐藏在这幢公寓里的惊天秘密，真相之下，没有无辜者，千丝万缕的事件之中，每个人都在自己的深渊里不断挣扎。