The inventor of a uniquely powerful new explosive has gone missing while working on a new poison gas for the British. Can Biggles and Ginger find him before the enemy does? Professor Max Beklinder has disappeared. He is the inventor of Linderite explosive, a Lucranian by birth but British by naturalization. The Professor was working on a secret poison gas for the British when he was reported as having been killed in a car accident in Unterhamstadt in Lucrania. Biggles is sent to find out if he is really dead and if not, to get him back. Written during the height of the Second World War in 1940, this classic adventure is a rare wartime adventure outside the Royal Flying Corps. Instead of having a relaxing time going to the pictures with his friends, biggles is instead seconded by British Intelligence to go to the castle of Van Stalhein, their old nemesis.