In the harrowing days after Alex and her co-workers survive a plane crash, they give up hope of immediate rescue from their deserted island in the Caribbean. To commemorate the lack of meaning time has for them anymore, they pile their watches at the low tide mark of their beach for the sea to carry the timepieces away.

In the short term, goats and fruit abound, but those resources will only last so long. The party uncovers more immediate concerns when they wake up one morning to find one of their number has disappeared during the night. In their search for him, they find his watch lying in a pool of blood. When they turn up no suspects or explanations, they carry on as best they can, albeit warily ... until it happens a second time.

The survivors conclude there is a killer in their midst, which leads to two important questions. Who will be next? And who or what is doing the killing? As the cycle repeats itself and their numbers continue to dwindle, anxiety and suspicion abound, leading to a third question - who will be last?