Hong Kong, 1960s: The old submarine-chaser USS Hibiscus, refitting in a Hong Kong dockyard before being handed over to the Nationalist Chinese, is suddenly ordered to the desolate island group of Payenhau. For Captain Mark Gunnar, who is driven by the memory of his torture at the hands of Viet Cong guerillas, the new command is a chance to even the score against a ruthless, unrelenting enemy. But Payenhau is very different from his expectations, and as the weather worsens, a crisis develops that Gunnar must face alone.