Capt. W.E. Johns 
Biggles Sorts It Out [EPUB ebook] 

The theft of Lord Langdon’s collection of rubies from Ferndale Manor in Surrey looked simple enough. ‘A bit too straightforward, ’ said Biggles. ‘These apparently simple cases have a trick of coming unstuck, ’ a remark which a flight to Africa and the events that followed proved only too true, though the ending when it came was so unpredictable that even Biggles was lost for words.