The gatecrashers

"Nick Everard and his son Paul return in this final chapter of the Everard saga. Paul commands a state-of-the-art midget submarine, sent to sneak up on the formidable German battleship Tirpitz and lay explosive charges. It's one step away from a suicide mission, but Paul must try-for if he fails, his father Nick's escort of an Arctic convoy hardly stands a chance."@en
"This last volume of the Nicholas Everard series is based on a true incident, Operation Source, when six midget submarines were towed underwater from Scotland to northern Norway by larger submarines and released there to attack Tirpitz."@en
"It seemed like mission impossible: the tiny X-craft midget submarine up against the Tirpitz, the mightiest battleship afloat, but Paul Everand must take his chance to gatecrash the Norwegian Fjords - past minefields, patrol craft, shore guns, steel nets and acoustic detection gear - and cripple the ship Churchill had called "the Beast". Even if he succeeded, the chances of escaping alive were slim. If he failed, Nick Everard, commanding Artic convoy PQ19, was in for a pounding."