When a training mission goes wrong, Sublieutenant Tom Thrush finds his brand-new career hanging by a thread. Desperate to redeem himself, he makes a rash wager – he’ll lead a squad in a mock attack, boarding and capturing the visiting gunboat Diana in record time. He hasn’t got a chance, and to make matters worse, there’s a visiting admiral watching the attack from her yacht.Tom, desperate, sneaks aboard the Diana through a gun port – and stumbles into the middle of something much worse than a training exercise. There’s a traitor aboard the Diana, planning to blow the admiral’s yacht out of the sky.Suddenly Tom is fighting for something much bigger than a foolish bet. If he loses, the admiral dies – and so does Tom.