he tenement house, and presently reached Retto's door.
His knock brought no response, and he stood for a moment, undecided
what to do. Then a bold idea came to him.

"I'll try the door and see if he's home," he said. "If he isn't,
there's no harm done. If he is, I can explain it somehow."

Larry, after a moment's hesitation to listen for any possible
movement on the other side of the portal, tried the door. It opened
easily for him, though it needed but a glance to show that the
apartment was empty and vacated. All the furniture was gone.

"He's skipped!" exclaimed Larry, as he struck a match and looked
around. "I guess he was afraid I'd find him. Well, I am more
determined than ever that I'll land this man. I wonder if he left
any clues behind?"

He lighted a jet of a wall fixture, for the gas had not been shut
off. In the glare he saw a scrap of paper lying on the floor. He
picked it up. As he glanced at it he gave a cry of astonishment.

"Who would have thought it!" exclaimed Larry to himself. "Of all the
strange things! I wonder I didn't connect him with the case before!
This explains why he was in front of the house."

For, the paper he had picked up was part of an envelope like those
which had contained the letters Grace received from her father. And
on the scrap was her name, but the envelope had been spoiled by a
blot of ink in writing the address. It had been torn up and thrown
away, to remain a mute bit of evidence.

"Mah Retto knows Mr. Potter!" exclaimed Larry. "Retto is the man who
mailed the letters for the missing millionaire. If I find him I can
make him tell me where Mr. Potter is! Now to trace my mysterious
East Indian friend!"

CHAPTER XXI

TRACING RETTO

Larry took another survey of the apartment to see if there were any
more clues that might aid him. But the one that had so unexpectedly
come to his hand was all he found. The place showed evidences of
having been hastily vacated.

"I'll see Mr. Jackson," he decided. "Perhaps he can tell me
something. He was interested in this queer man."

He lost no time in going to the rooms of his friends. They were glad
to see him, and asked a number of questions about his mother,
sisters and brother. But Larry, as soon as he could, turned the
subject to Retto.

"He's gone," he told Mr. Jackson.

"I supposed he had. I saw the janitor taking his things from the
room this morning."

"Do you know where he went to?" asked the young reporte