“What had he heard?  What was the man doing?” questioned Jane anxiously.  Even though she believed Frederic Hoff an alien enemy, even though she was all but sure that he was a murderer, she kept finding herself always hoping for something in his favor.  He seemed far too nice and entertaining to be engaged in any nefarious, underhanded, despicable machinations.  Yet she had seen him masquerading as a British officer.  She could not doubt the evidence of her own eyes.

“What happened was this,” continued Dean.  “A woman—­one of the society lot—­was driving down Park Avenue day before yesterday morning in her motor.  It had been raining, and the streets were muddy.  At one of the crossings a British officer stopped to let the car pass.  One of the wheels hit a rut, and his uniform was all splashed with mud.  He burst into a string of curses—­German curses.”

“He cursed in German?” cried Jane.

“Sure,” said Dean.  “On the impulse of the moment he forgot his role and revealed his true self—­an arrogant Prussian officer.”

“What did the woman do?”

“Reported him to the first policeman she met, but by that time he had vanished, of course.”

“What did Chief Fleck think about it?”

“He didn’t seem to take the story seriously.”

“Do you suppose it could have been Mr. Hoff?”

“It must have been he, or one of his gang, at any rate.  I don’t see why the Chief does not order his arrest at once.  He is far too dangerous to be at large.”

“There’s no real evidence against him yet,” protested Jane, “not against the young man, at least.”

“Didn’t we both see him in British uniform?”

“Yes,” admitted the girl.

“Well, that’s proof, isn’t it?  A man with a German name in British uniform in wartime can’t be up to any good.”

“Still we have no actual evidence against him.  We don’t know what he was doing.”

“I’d arrest him then for murder and get the evidence that he is a spy afterward.  It would be easy to fasten the murder of K-19 on him.  There’s no doubt that he did that.”

“Has a witness been found?” asked Jane with a quick catch of the breath.  Somehow she never had been able to persuade herself that the man next door, whatever else he might be, had really committed that brutal murder.

“No, there’s no actual witness, but it could be proved by circumstantial evidence.  K-19, the man whose work you took up, had instructions to shadow young Hoff to his home.  At two in the morning he relieved another operative.  At three you yourself saw him shadowing Hoff.”

“I saw two men on the sidewalk,” corrected Jane.  “One of them was Frederic Hoff.  I did not see the other distinctly enough to identify him.  I saw no murder.  I merely saw the two of them run around the corner.”

“Look here,” said Dean sharply, not wholly succeeding in suppressing a note of jealousy in his tones, “I believe you are trying to shield Frederic Hoff.  What is he to you?  Has he won you over to his side?”