When Temeraire's trials are cut short and she is ordered to the Far East to reinforce the fleet against a threat from Red China, her captain, David Jermain, knows that this is no routine exercise in flag-waving. And once in Asian waters, he and his submarine find themselves involved in a hidden undeclared conflict beneath the sea.

While politicians haggle over a situation which could hold the seeds of a full-scale war, Commander Jermain must keep his faith in himself and in his new ship's potential - even when ordered to take the Temeraire to the edge of catastrophe.