“Eleven is doing pretty well to-night,” said Olma as we bent over the charts. “Three has a degree or so of fever but has been fairly quiet. Oh, by the way, have you the key to the south door?”

“No.”

She frowned.

“I couldn’t find it. I had to leave the south door unlocked.”

“Couldn’t find it!”

“No. It wasn’t anywhere about the desk.”

“Did you look in the lock?”

“Of course, Miss Keate. And I asked the other girls. No one has seen it since morning.”

In view of the existing circumstances, I suppose it was natural that I should feel immediately alarmed. After Olma had gone wearily away to bed I gave the chart desk and its vicinity a thorough search.

“What on earth are you doing?” asked Maida, coming along just as I had taken all the charts out of the rack and was feeling about with my fingers in the recesses left empty.