Again Kennedy had started to dissect.

“Ah,” he went on, “this is the real thing, though, only a little different from the other.  A dry battery gives a spark when the lid is slipped back.  See, the explosive is in a steel pipe.  Sliding the lid off is supposed to explode it.  Why, there is enough explosive in this to have silenced a dozen Haddons.”

“Do you think he could have been kidnapped or murdered?” I asked.  “What is this, anyhow—­gang-war?”

“Or perhaps bribed?” suggested Carton.

“I can’t say,” ruminated Kennedy.  “But I can say this:  that there is at large in this city a man of great mechanical skill and practical knowledge of electricity and explosives.  He is trying to make sure of hiding something from exposure.  We must find him.”

“And especially Haddon,” Carton added quickly.  “He is the missing link.  His testimony is absolutely essential to the case I am building up.”

“I think I shall want to observe Loraine Keith without being observed,” planned Kennedy, with a hasty glance at his watch.  “I think I’ll drop around at this Mayfair I have heard so much about.  Will you come?”

“I’d better not,” refused Carton.  “You know they all know me, and everything quits wherever I go.  I’ll see you soon.”

As we drove in a cab over to the Mayfair, Kennedy said nothing.  I wondered how and where Haddon had disappeared.  Had the powers of evil in the city learned that he was weakening and hurried him out of the way at the last moment?  Just what had Loraine Keith to do with it?  Was she in any way responsible?  I felt that there were, indeed, no bounds to what a jealous woman might dare.

Beside the ornate grilled doorway of the carriage entrance of the Mayfair stood a gilt-and-black easel with the words, “Tango Tea at Four.”  Although it was considerably after that time, there was a line of taxi-cabs before the place and, inside, a brave array of late-afternoon and early-evening revellers.  The public dancing had ceased, and a cabaret had taken its place.

We entered and sat down at one of the more inconspicuous of the little round tables.  On a stage, at one side, a girl was singing one of the latest syncopated airs.

“We’ll just stick around a while, Walter,” whispered Craig.  “Perhaps this Loraine Keith will come in.”

Behind us, protected both by the music and the rustle of people coming and going, a couple talked in low tones.  Now and then a word floated over to me in a language which was English, sure enough, but not of a kind that I could understand.

“Dropped by a flatty,” I caught once, then something about a “mouthpiece,” and the “bulls,” and “making a plant.”

“A dip—­pickpocket—­and his girl, or gun-moll, as they call them,” translated Kennedy.  “One of their number has evidently been picked up by a detective and he looks to them for a good lawyer, or mouth-piece.”