"Suffering rattlesnakes! What am I getting into?" murmered Biggles, a ghost of a smile softening his face. "First I'm sworn into the German Air Force; now, of all things, Im a full-blown Gestapo agent."

While on a reconnaissance mission, Biggles gets caught up in a German invasion of Norway. Constantly trying to stay one step ahead of the the enemy gets him into some desperate straits - and some outrageous pieces of bluff. With his old enemy Von Stalhein hot on his trail, Biggles knows he is just a hairsbredth away from capture and the ultimate horror of a Nazi firing squad.

goodreads summary

Biggles' old enemy Von Stalhein has heard that he is on a recon mission in Norway and is determined to track him down.