In "The Fifth Elephant" Acting Captain Colon (normally known as Sergeant Fred Colon) is obsessed about missing sugar lumps. During the course of the story more and more sugar lumps go missing.
It started with this passage:
Visit saluted. It was probably the only way to get out of there alive. One of Colon's eyes was twitching.
"However, you could redeem yourself," said Colon, "if you was to tell me who has been stealing, I said stealing, the sugar lumps."
"I knows there was forty-three last night. I counted 'em very thoroughly. There's fortyone this morning, constable. And they're locked in the desk. Can you explain that?"
If Visit had been suicidal and honest, he would have said: well, captain, while of course I think you have many worthy qualities, I have known you count your fingers twice and come up with different answers.
"Er... mice?" he said weakly.
"Hah! Off you go, lance-constable, and just you think about what I said!"
However it was picked up several times in the story for example in a dialog with the Patrician:
"Sah!" Colon leaned forward, his face twisted in a ghastly grimace of conspiratoriality. "Between you and me, sir, Commander Vimes was a good deal too soft on them. He let them get away with too much. No sugar is safe, sah!"
I have read the story twice but I still don't know what happened to the sugar lumps. Is there any hint or actual explanation (that I overlooked) in the story?