The old submarine-chaser USS Hibiscus, re-fitting in 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 - driven by the memory of his torture at the hands of Viet Cong guerrillas - 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.