"They measure distance," he explained to Casimer, in his usual slow, halting monotone, "from demons."

He seemed about to ask a question when he too heard the song, probably quite a bit more keenly with his ears that seemed big even as elves went.

"I did," he confirmed, as the final three scales that emerged from his pack settled on each of their shoulders. They bowed in turn to Kit and Casimer. They may have been strange little devices, but at least they were polite.

"I doubt it needs to be said, but let us proceed with caution."