“The traitress—­it is Marie!” she shrieked.

For a moment, obtusely, I did not understand.

“She has made a secret appointment with him,” she cried.

At last I saw the truth.  Paula Lowe had fallen in love with the man she had sworn to kill!

CHAPTER II

THE ELECTRO-MAGNETIC GUN

“What shall we do?” demanded Burke, instantly taking in the dangerous situation that the Baron’s sudden change of plans had opened up.

“Call O’Connor,” I suggested, thinking of the police bureau of missing persons, and reaching for the telephone.

“No, no!” almost shouted Craig, seizing my arm.  “The police will inevitably spoil it all.  No, we must play a lone hand in this if we are to work it out.  How was Fortescue discovered, Burke?”

“Sitting in a chair in his laboratory.  He must have been there all night.  There wasn’t a mark on him, not a sign of violence, yet his face was terribly drawn as though he were gasping for breath or his heart had suddenly failed him.  So far, I believe, the coroner has no clue and isn’t advertising the case.”

“Take me there, then,” decided Craig quickly.  “Walter, I must trust Miss Lowe to you on the journey.  We must all go.  That must be our starting point, if we are to run this thing down.”

I caught his significant look to me and interpreted it to mean that he wanted me to watch Miss Lowe especially.  I gathered that taking her was in the nature of a third degree and as a result he expected to derive some information from her.  Her face was pale and drawn as we four piled into a taxicab for a quick run downtown to the laboratory of Fortescue from which Burke had come directly to us with his story.

“What do you know of these anarchists?” asked Kennedy of Burke as we sped along.  “Why do you suspect them?”

It was evident that he was discussing the case so that Paula could overhear, for a purpose.

“Why, we received a tip from abroad—­I won’t say where,” replied Burke guardedly, taking his cue.  “They call themselves the ‘Group,’ I believe, which is a common enough term among anarchists.  It seems they are composed of terrorists of all nations.”

“The leader?” inquired Kennedy, leading him on.

“There is one, I believe, a little florid, stout German.  I think he is a paranoiac who believes there has fallen on himself a divine mission to end all warfare.  Quite likely he is one of those who have fled to America to avoid military service.  Perhaps, why certainly, you must know him—­Annenberg, an instructor in economics now at the University?”

Craig nodded and raised his eyebrows in mild surprise.  We had indeed heard of Annenberg and some of his radical theories which had sometimes quite alarmed the conservative faculty.  I felt that this was getting pretty close home to us now.

“How about Mrs. Annenberg?” Craig asked, recalling the clever young wife of the middle-aged professor.