A wartime sub prowls the Med...but who is the enemy?

It is 1942. Lt Harry Gilmour has already made a name for himself in the Royal Navy submarine service. He has risked his life to save a fellow seaman after his first boat, HMS Pelorus is rammed and sunk in the North Sea. He’s played a leading role in HMS Trebuchet’s epic foray into a fjord in the then-neutral Soviet Union, to scatter German ships secretly assembling to invade Iceland. And as number three on HMS Umbrage in the Mediterranean, he had assumed command after her skipper had been lost overboard, and gone on to attack an Italian cruiser squadron.

Yet he is only an RNVR officer – a Wavy-Navy wunderkind. But when he gets his own submarine as the Royal Navy supports Montgomery’s Eighth Army campaign, an unexpected enemy looms on the horizon. Harry comes face to face again with Captain Charles ‘Bonny Boy’ Bonalleck, skipper of the doomed Pelorus and now in charge in the Med. Harry blames the Bonny Boy for the tragedy – and has told him to his face.

Can Harry trust Bonalleck’s offer to let bygones be bygones? Will the mission he is sent on help end the war – or end his career?