Like all young men of a certain age, Harry Gilmour had his own notion of how a naval battle should be. This wasn't it.

Norway, 1940: Sub Lieutenant Harry Gilmour's first encounter with battleship action is not the adventure he had hoped for. Faced with a thankless task and ill equipped to handle it, Gilmour's inexperience leads to a damning allegation. His future hangs in the balance.

But then Lieutenant Peter Dumaresq steps in to offer him a lifeline--an advanced navigation course that will take him aboard a crack submarine, HMS Pelorus, under the command of a Royal...