Old Ugly-Face by Talbot Mundy

And so, in the black magician's dim blue lantern light, Major von Klaus of the Gestapo, on his hands and knees, believing to the last second that Andrew was bluffing in fear of his life, unlocked and opened the brown canvas bag, with Andrew's key. The truth staggered him. Andrew had told the truth. The exact truth. It was an effrontery. Before he could recover, his chance was gone to invent a string of lies and create a new crisis. Andrew's voice spoiled it, sonorously: "My gift--to the lord magician--Lung-gom-pa."

Elsa translated the short speech quickly into Tibetan. The ten brigands drew in their breath at the reckless use of the magician's name. But the old man himself ignored the breach of manners. He was like a big dark parrot on a perch. His red-rimmed eyes became a picture of possessiveness qualified by a secret new fear born of knowledge of evil. Not even a vulture ever had such eyes as those. Perhaps the Sphinx did. They were not totally unlike the eyes of a dog with a bone. He had the bone. Now what?