A former R.A.F. colleague, Squadron Leader "Dizzy" Digswell, approaches Biggles with a proposal to go out and recover a treasure from archaeological ruins which he has discovered and believes to be the fabled lost city of Ophir. They need a private aircraft and so Biggles forms a syndicate where each of the partners puts in money to fund the expedition. Bertie and Ginger are sent to accompany Digswell to the site near Aden but soon, Biggles gets news that they are in trouble. Illustrated by Leslie Stead.