The students were in unanimous agreement and, at this point, Dr. Henderson came to an abrupt stop in his lecture. Suddenly, an expression of surprise appeared on his face. It was succeeded by an exclamation of triumph. And he simply vanished from the spot.
He didn't fade away, rise, drop into the floor, or take any time vanishing. He simply stopped being there.
He just wasn't there any more.
The police searched his room in the nearby Vanderbilt Arms Hotel. They turned a portrait of the missing math professor to the newspapers to publish. Arbright University offered a reward of one hundred dollars to anyone who had seen him.
The police also found a savings pass book in his room. It had a balance of three thousand eight hundred and forty dollars, which had been built up to that figure by steady monthly deposits over a period of years. It also had a withdrawal of three hundred and twenty dollars two days before the disappearance. They were sure they were on the path to a motive. This avenue of exploration came to an abrupt end with the discovery that he had traded in his last year's car on a new one, and that sum had been necessary to complete the deal.
After the third day the blackboard had been erased and the classroom released for its regular classes. Police enthusiasm dropped to the norm of what they called legwork. Finding out who the missing man's acquaintances and friends were, calling on them and talking to them in the hopes of picking up something they could go on.
They passed Martin Grant by because they had heard from him in their initial work. In fact, he had been a little too present for their tastes.