“Well,” continued Frank, “somehow Markham made paste—probably out of a piece of bread. He compiled that letter.”

“But how did he get it mailed?” suggested Bob.

“Suppose he was a prisoner, and threw it from a window into the road, chancing its discovery and mailing by some passer-by.”

“That’s so,” nodded Darry. “I believe you are correct in your conclusions, Frank. As to the mailing lists, which Markham also had with him, that’s a later mystery to develop.”

“Now then,” spoke Frank, “I think I can also figure out something else. I believe that Dale Wacker followed Markham. He was probably right on his heels when Markham entered this building. Markham saw him, got scared, and, to evade him, ran up to the third floor. There he found no rooms open to hide in. He was cornered, intimidated, maybe attacked by Wacker. He thought of that two hundred dollars, and dropped it behind the fuel box. Then—”

Frank paused here, and shook his head in doubt and perplexity.

“Poor Markham,” commented Bob. “It looks likely that he is held a prisoner somewhere. Maybe because his captor knows he threw away that package of money, and won’t let him go free till he tells where. Anyhow, he’s a good one, surmounting all the difficulties of his situation and getting that letter to you.”

“I suppose you will take up the mail order business actively again, now you are in funds?” suggested Darry.

“Surely,” said Frank. “Here, take the money and hurry up the catalogue.”

Frank felt immensely relieved as he proceeded to his office. His mind, however, was full of plans looking to the discovery of Markham’s place of captivity.