"Then, Chief, I don't see any use trying that lead. It begins and ends in air." "It most certainly does! We'll cross it out. The next call for our investigation----" "Which was?" asked Delaney, waking up. "Which was the one notifying Stockbridge that he had about reached his span of life on this earth. I was there in that library when the call came in. Again, from the millionaire's description, this time, we have the thin, whispering voice on the wire. The man was probably the same. He mentioned the cemetery letter which would establish that fact." "I'm following you, Chief. Go on!" Drew picked out a second sheet of paper from his pile. "We went after this call at the time, or soon after the time it was sent in," he said, tapping the sheet with his fingers. "I called the office here and had Harrigan get in touch with George Westlake, third vice-president of the telephone company. Westlake got busy." Delaney eyed his unpolished shoes with a sage wink. "Westlake turned things over," continued the detective. "He made a most thorough investigation. We have his word that there is no record of this call! The wire-chief at Gramercy Hill Exchange declares that it never went through the switchboard. That the connection had been made on the outside." "From the air?" "Looks that way. They tried everything and questioned everybody. No one talked with Stockbridge through the switchboard at Gramercy Hill, at or near that hour. Therefore, we must conclude, that, insomuch as I know somebody _did_ talk with him at that hour, the connection was made, either in the junction-box in the alley or behind the switchboard at Gramercy Hill Exchange." "How about underground, Chief?" "Impossible! That is--almost impossible. The cables are in conduit and sheathed with lead. It would be a poor place to tap in on a line. I'm going to presume that the man who tapped in knew his business. The junction-box in the alley is under suspicion. I think it was done there, in this manner." Drew paused and picked up a third sheet of hurriedly-written notes. "A junction-box," he said, "is merely a small switchboard where the conduit ends and the house connections begin. It would have been easy for an expert to disconnect the two leads which led into Stockbridge's library, ring up with a low tension magneto, and then cut in with a testing set and a battery current and do the talking. That is what the trouble-man told us might have been done. He found no signs of tampering. He saw a tall man escaping down the alley. It would seem, Delaney, that this tall man is the one we're after. Perhaps, as you said, he left footprints. But footprints, like fingerprints, are not much use until you get the man who made them." "What d'ye deduct in this second call--Chief?" "That we've run squarely up against a blind wall. We'll drop it for a time and go to the third call." "When was that?"