Lieutenant Commander Potter rejoins Special Force Orca in the Mediterranean in time for the Italian surrender and to take command of one of their commandeered submarines to use against their former Ally, Germany. After only one day with his new boat, unexpected and potentially lethal events occur that call for some speedy lateral thinking on his part.
His beloved leader Commodore Barr is no beginner at thinking out of the box himself and with the Allies bogged down on the beaches of Salerno and a disastrous second Dunkirk looming, he formulates an audacious plan to help by landing a strong force of his commandoes to disrupt and hinder the enemy behind their own lines. He faces more resistance than he has envisaged and from an unexpected quarter and it is only by virtue of his Special Force Orca having independent status that he can overcome a new enemy the inexperienced and Anglophobic American General in charge of the Landings.
He goes ahead with his plan and, using a creative diversion, lands a strong force on the coast to the north of the beleaguered Allied troops.
Sergeant Bushel, of the Royal Marines, faces his biggest challenge yet when he takes command of the landing force and finds he has a spy in their midst...