Capt. W.E. Johns 
Biggles Takes It Rough [EPUB ebook] 

Who scuttled Rod Macaster’s cabin cruiser at its moorings, and how did the smell of burning peat come to pervade the island castle which had been empty so long? Biggles found these tantalizing questions no easier to answer than his attempt to ferret out the enemy on this remote island off Scotland’s western coast, but he was never a man to leave a job half done…