Since then she has not been back to the hotel." "I don't like that," said Tarling, a little troubled.

"I wished her to be under observation as much for her own protection as anything else.

I wish you would keep a man at the hotel and telephone me just as soon as she returns." Whiteside nodded.
"I've anticipated your wishes in that respect," he said.

"Well, what is the next move ?" "I'm going to Hertford to see Miss Rider's mother; and incidentally, I may pick up Miss Rider, who is very likely to have gone home." Whiteside nodded.
"What do you expect to find out from the mother ?" he asked.
"I expect to learn a great deal," said Tarling.

"There is still a minor mystery to be discovered.