“Hold on,” said Frank, but the wicket went shut with a sudden snap.

“Of course this is the place,” thought Frank. “That’s something to know. Hello—”

Five steps down the stairs Frank started. Something had struck his shoulder. As he turned he noticed the window being pulled to. Also at his feet the object that had struck him.

It was a little piece of tin—around it was tied a fragment of coarse manilla paper. Frank picked it up. He slipped it into his pocket and descended to the street. Turning the corner he untied the paper. It was scrawled over, and read:

“Keep cool. Be shady. Things working. Important. Midnight.”

Frank had to smile at all this serio-tragic phraseology.

“Stet wrote that,” he said. “Still the dark and mysterious detective! Probably enjoying it. He usually means something though, for all his extravagant ways of mystery. That means he has news to tell me. But where does he expect to see me at midnight? And why midnight?

“Ah! Brr-rr-r! Hist! Good old Stet! He’ll probably do something sensational soon, but meantime I must pursue my investigations.”

These did not result in much. Frank went to the post-office. The postmaster told him that twice a day either Dale Wacker or an old man who was evidently associated with him brought a great many letters to mail. In return they received as many as forty letters a day. They presented a good many money orders, always for the same amount—eleven dollars.

The afternoon was nearly gone by this time. Frank called at the town hall but found that the marshal had gone home to sleep until midnight.