Many reasons, I found, had been assigned for the disappearances.  I knew that there must be many causes at work, that no one cause could be responsible for all or perhaps a majority of the cases.  There were suicides and murders and elopements, family troubles, poverty, desire for freedom and adventure; innumerable complex causes, even down to kidnapping.

The question was, however, which of these causes had been in operation in the case of Betty Blackwell?  Where had she gone?  Where had this whole army of vanishers disappeared?  Were these disappearances merely accidents—­or was there an epidemic of amnesia?  I could bring myself to no such conclusions, but was forced to answer my own queries in lieu of an answer from Kennedy, by propounding another.  Was there an organized band?

And, after I had tried to reason it all out, I still found myself back at the original question, as I rejoined Kennedy at the laboratory, “Where had they all—­where had Betty Blackwell gone?”

II

THE BLACK BOOK

I had scarcely finished pouring out my suspicions to Kennedy when the telephone rang.

It was Carton on the wire, in a state of unsuppressed excitement.  Kennedy answered the call himself, but the conversation was brief and, to me, unenlightening, until he hung up the receiver.

“Dorgan—­the Boss,” he exclaimed, “has just found a detectaphone in his private dining-room at Gastron’s.”

At once I saw the importance of the news and for the moment it obscured even the case of Betty Blackwell.

Dorgan was the political boss of the city at that time, apparently entrenched, with an organization that seemed impregnable.  I knew him as a big, bullnecked fellow, taciturn to the point of surliness, owing his influence to his ability to “deliver the goods” in the shape of graft of all sorts, the archenemy of Carton, a type of politician who now is rapidly passing.

“Carton wants to see us immediately at his office,” added Craig, jamming his hat on his head.  “Come on.”

Without waiting for further comment or answer from me, Kennedy, caught by the infectious excitement of Carton’s message, dashed from our apartment and a few minutes later we were whirling downtown on the subway.

“You know, I suppose,” he whispered rather hoarsely above the rumble and roar of the train, but so as not to be overheard, “that Dorgan always has kept a suite of rooms at Gastron’s, on Fifth Avenue, for dinners and conferences.”

I nodded.  Some of the things that must have gone on in the secret suite in the fashionable restaurant I knew would make interesting reading, if the walls had ears.

“Apparently he must have found out about the eavesdropping in time and nipped it,” pursued Kennedy.

“What do you mean?” I asked, for I had not been able to gather much from the one-sided conversation over the telephone, and the lightning change from the case of Betty Blackwell to this had left me somewhat bewildered.  “What has he done?”