Тhe Eagle Has Flown by Jack Higgins

As an increasingly isolated and insane Hitler pursues his hopeless war, betrayal and treachery reach the highest levels of the Third Reich.
German intelligence knows that paratroop officer Steiner survived "Operation Eagle," the bungled assassination attempt on Winston Churchill, and is now a POW somewhere in London. Reichsfuhrer Himmler wants him back -- at any cost -- and puts his top espionage agents in charge of the perilous rescue mission.
Racing from the nightclubs of Lisbon to Hitler's opulent country retreat to the damp streets of London, Himmler's men get closer to their target -- and to the shattering true objective of their mission....