"No motive of course?" asked The Thinking Machine.
"Well, the question of motive isn't exactly clear but our further investigations will bring it out all right," the detective admitted. "I should imagine the motive to be jealousy. Of course the story of Knight not knowing where his stiletto is has no weight."
Detective Mallory was so charmed with himself that he offered cigars to his visitors-an unusual burst of generosity-and Hatch was so deeply thoughtful that he accepted. The Thinking Machine never smoked.
"May I see the stiletto and cane?" he asked instead.
The detective was delighted to oblige. He watched the scientist with keen satisfaction as that astute gentleman squinted at the slender blade, still stained with blood, and then as he examined the lower part of the cane. Finally the scientist thrust the long blade into the hollow stick and screwed the handle in. It fitted perfectly. Detective Mallory smiled.
"I don't suppose you'll try to put a crimp in me this time?" he asked jovially.
"Very clever, Mr. Mallory, very clever," replied The Thinking Machine, and with Hatch trailing he left headquarters.
"Mallory will swell like a balloon after that," Hatch commented grimly.
"Well, he might save himself that trouble," replied the scientist crustily. "He has the wrong man."
The reporter glanced quickly into the inscrutable face of his companion.
"Didn't Knight do it?" he asked.
"Certainly not," was the impatient answer.
"Who did?"
"I don't know."
Together they went on to the theatre from which Miss Oliver had been removed the night before. There a few words with the manager gained permission to look at the Oliver box-a box which the Olivers held only on alternate nights during the opera season. It was on the first balcony level, to the left as they entered the house.
The first three rows of seats in the balcony ran around to and stopped at the box, one of four on that level and the furthest from the stage. The Thinking Machine pottered around aimlessly for ten minutes while Hatch looked on. He entered the box two or three times, examined the curtains, the partitions, the floor and the chairs after which he led the way into the lobby.
There he excused himself to Hatch and stopped in the manager's office. He remained only a few minutes, afterwards climbing into a cab in which he and Hatch were driven back to police headquarters.
After some wire pulling and a good deal of red tape The Thinking Machine and his companion were permitted to see Knight. They found him standing at the barred cell door, staring out with weary eyes and pallid face.
The Thinking Machine was introduced to the prisoner by Hatch who had previously tried vainly to induce the young man to talk.
"I have nothing to say," Knight declared belligerently. "See my attorney."
"I would like to ask three or four questions to which you can have no possible objection," said The Thinking Machine. "If you do object of course don't answer."
"Well?" demanded the prisoner.
"Have you ever travelled in Europe?"
"I was there for nearly a year. I only returned to this country three months ago."
"Have you ever been interested in any other woman? Or has any other woman ever been interested in you?"
The prisoner stared at his questioner coldly.
"No," he responded, emphatically.
"Your answer to that question may mean your freedom within a few hours," said The Thinking Machine quite calmly. "Tell me the truth."
"That is the truth-on my honour."
The answer came frankly, and there came a quick gleam of hope in the prisoner's face.
"Just where in Italy did you buy that stiletto cane?" was the next question.
"In Rome."
"Rather expensive?"
"Five hundred lira-that is about one hundred dollars."
"I suppose they are very common in Italy?"
"Yes, rather."
Knight pressed eagerly against the bars of his cell and gazed deeply but uncomprehendingly into the quiet squinting blue eyes.
"There has never been any sort of a quarrel-serious or otherwise between you and Miss Oliver?"
"Never," was the quick response.
"Now, only one more question," said The Thinking Machine. "I shall not ask it to hurt you." There was a little pause and Hatch waited expectantly. "Does it happen that you know whether or not Miss Oliver ever had any other love affair?"
"Certainly not," exclaimed the young man, hotly. "She was just a girl-only twenty, out of Vassar just a few months ago and-and--"
"You needn't say any more," interrupted The Thinking Machine. "It isn't necessary. Make your plans to leave here to-night, not later than midnight. It is now four o'clock. To-morrow the newspapers will exonerate you."
The prisoner seemed almost overcome by his emotions. He started to speak, but only extended an open hand through the bars. The Thinking Machine laid his slender fingers in it with a slight look of annoyance, said "Good day" mechanically and he and Hatch went out.
The reporter was in a sort of a trance, not an unusual condition in him when in the company of his scientific friend. They climbed into the cab again and were driven away. Hatch was thinking too deeply to note the destination when the scientist gave it to the cabby.
"Do you actually anticipate that you will be able to get Knight out of this thing so easily?" he asked incredulously.
"Certainly," was the response. "The problem is solved except for one or two minor points. Now I am proving it."
"But-but--"
"I will make it all clear to you in due time," interrupted the other.
They were both silent until the cab stopped. Hatch glanced out and recognized the Oliver home. He followed The Thinking Machine up the steps and into the reception hall. There the scientist handed a card to the servant.
"Tell Mr. Oliver, please, that I will only take a moment," he explained.