Biggles is sent to Jamaica to recover a cache of secret papers - blueprints of German secret weapons under development at the end of World War II. Their owner, Werner Wolff, had been living in Jamaica under an assumed name for many years. Unfortunately, Wolff had died without revealing where he hid his papers. There are few clues to go on - only a tracing of a oval shape with a little square on it. And Biggles must move fast because his old adversary, von Stalhein, now in the employ of a secret service behind the Iron Curtain, is in Jamaica hunting for the same thing. Illustrated by Leslie Stead.