November 1983: Three hundred feet beneath the Atlantic, submarine Lieutenant Bill Guth and his fellow officers suddenly receive the order they've long-dreaded - to launch their nuclear missiles in a retaliatory strike against the USSR. But in the unexpected chaos that follows, one person on board lies dead...

Norfolk, 2019: Bill Guth's annual family gathering is interrupted when a historian turns up unannounced to ask about the near-apocalyptic incident back in 1983. Bill refuses to answer. But that night, the historian is brutally murdered.

Bill and his family are thrown under suspicion. What happened all those years ago? Just how much is Bill to blame for events in the past, and indeed the present? As the layers of history reveal themselves, it becomes clear there is a killer at work who will stop at nothing to keep the secrets of 1983 where they belong...