“That’s telautomatics, and that is what has been stolen from our navy and dimly sensed by you clever newspaper men, from whom even the secret service can’t quite hide everything.  The publication of the rumour alone that the government knows it has lost something has put the secret service in a hole.  What might have been done quietly and in a few days has got to be done in the glare of the limelight and with the blare of a brass band—­and it has got to be done right away, too.  Come on, Walter.  I’ve thrown together all we shall need for one night—­and it doesn’t include any pajamas, either.”

A few minutes later we met our friend Burke of the secret service at the new terminal.  He had wired Kennedy earlier in the day saying that he would be in New York and would call him up.

“The plans, as I told you in my message,” began Burke, when we had seated ourselves in a compartment of the Pullman, “were those of Captain Shirley, covering the wireless-controlled submarine.  The old captain is a thoroughbred, too.  I’ve known him in Washington.  Comes of an old New England, family with plenty of money but more brains.  For years he has been working on this science of radio-telautomatics, has all kinds of patents, which he has dedicated to the United States, too.  Of course the basic, pioneer patents are not his.  His work has been in the practical application of them.  And, Kennedy, there are some secrets about his latest work that he has not patented; he has given them outright to the Navy Department, because they are too valuable even to patent.”

Burke, who liked a good detective tale himself, seemed pleased at holding Kennedy spellbound.

“For instance,” he went on, “he has on the bay up here a submarine which can be made into a crewless dirigible.  He calls it the Turtle, I believe, because that was the name of the first American submarine built by Dr. Bushnell during the Revolution, even before Fulton.”

“You have theories of your own on the case?” asked Craig.

“Well, there are several possibilities.  You know there are submarine companies in this country, bitter rivals.  They might like to have those plans.  Then, too, there are foreign governments.”

He paused.  Though he said nothing, I felt that there was no doubt what he hinted at.  At least one government occurred to me which would like the plans above all others.

“Once some plans of a submarine were stolen, I recall,” ruminated Kennedy.  “But that theft, I am satisfied, was committed in behalf of a rival company.”

“But, Kennedy,” exclaimed Burke, “it was bad enough when the plans were stolen.  Now Captain Shirley wires me that some one must have tampered with his model.  It doesn’t work right.  He even believes that his own life may be threatened.  And there is scarcely a real clue,” he added dejectedly.  “Of course we are watching all the employes who had access to the draughting-room and tracing everybody who was in the building that night.  I have a complete list of them.  There are three or four who will bear watching.  For instance, there is a young attache of one of the embassies, named Nordheim.”