A disgraced officer risks his life to help his childhood friends in battle.

A German submarine is sent to the Orkney Isles in 1917 to sink the British fleet.

10 strangers are summoned to a remote island and while they are waiting for the mysterious host to appear, a recording levels serious accusations at each of the guests, including Judge Francis J. Quinncannon and Dr. Edward G. Armstrong, and soon they start being murdered, one by one. As the survivors try to keep their wits, they reach a disturbing conclusion: one of them must be the killer.