"I don't blame you," exclaimed Bob, and after he had returned the car to its place in the garage he came back to the house to wait until his father should have finished the note he was writing. When it was ready Mr. Cook handed it to Bob, who at once started for the Wernbergs' house, accompanied by Hugh. They discussed the recent turn of events in the mystery and were somewhat at a loss as to what their next move should be. Now that the old deserted house was a thing of the past they did not know where to look for the seat of the conspiracy. They did decide, however, that in so far as it was possible they would keep watch on number twelve eighty-two Elm Street. They mounted the front steps of the Wernbergs' house, and Bob advanced toward the door bell. Before he rang it, however, he spied an envelope lying at his feet, half concealed under the door mat. He stooped to pick it up, and as he glanced at it he uttered an exclamation of surprise. "Look, Hugh," he exclaimed. The envelope was of plain white paper and addressed to Mr. Wernberg. There was no street number on it, merely the name. This in itself was not particularly odd, nor was it the cause of Bob's surprise. On the other side of the envelope, however, was scrawled a drawing. It was the picture of an alligator. CHAPTER XVII A MESSAGE "Well, Hugh, what do you think about that?" demanded Bob. Hugh looked blankly at the rude drawing on the back of the envelope. "I don't know," he said slowly. "Why should they send Mr. Wernberg one of these?" "Unless it's a message from one member of the gang to another." "But Mr. Wernberg is in the hospital." "The others may not know that." "That's true," Hugh agreed. "This handwriting is the same as that on the messages that came to your father and to Heinrich too." "I know it, and the same as in the list we found in the old house." "What do you suppose the alligator stands for?" "I've no idea. Why did they steal Percy?" "Anyway we'd better ring the bell and deliver our message. We can't stand out here on the porch all day, you know." Bob pushed the electric bell, and almost instantly the front door was opened by Frank Wernberg. It would seem as if he had been behind the door waiting all the time. His close-cropped light hair bristled fiercely, and his nose was still slightly swollen; his chin also was still raw where Bob had planted his fist the day before. Bob thought how much longer ago than that it seemed; so many things had happened in the last two days. "What are you doing here?" demanded Frank brusquely. Bob and Hugh had been so surprised by the sudden opening of the door that for a moment neither one of them replied. "What do you want?" exclaimed Frank. "We've got a letter for your mother," said Bob. Frank glared at them under lowering brows. "Who from?" he asked. "That's for her to find out," said Bob. "It's addressed to her you see."