The headmaster was in his garden.  Thither Mr. Downing made his way, the boot-bearing Psmith in close attendance.

The Head listened to the amateur detective’s statement with interest.

“Indeed?” he said, when Mr. Downing had finished.

“Indeed?  Dear me!  It certainly seems—­It is a curiously well-connected thread of evidence.  You are certain that there was red paint on this boot you discovered in Mr. Outwood’s house?”

“I have it with me.  I brought it on purpose to show to you.  Smith!”

“Sir?”

“You have the boot?”

“Ah,” said the headmaster, putting on a pair of pince-nez, “now let me look at—­This, you say, is the—?  Just so.  Just so.  Just....  But, er, Mr. Downing, it may be that I have not examined this boot with sufficient care, but—­Can you point out to me exactly where this paint is that you speak of?”

Mr. Downing stood staring at the boot with a wild, fixed stare.  Of any suspicion of paint, red or otherwise, it was absolutely and entirely innocent.

CHAPTER L 

THE DESTROYER OF EVIDENCE

The boot became the centre of attraction, the cynosure of all eyes.  Mr. Downing fixed it with the piercing stare of one who feels that his brain is tottering.  The headmaster looked at it with a mildly puzzled expression.  Psmith, putting up his eyeglass, gazed at it with a sort of affectionate interest, as if he were waiting for it to do a trick of some kind.

Mr. Downing was the first to break the silence.

“There was paint on this boot,” he said vehemently.  “I tell you there was a splash of red paint across the toe.  Smith will bear me out in this.  Smith, you saw the paint on this boot?”

“Paint, sir!”

“What!  Do you mean to tell me that you did not see it?”

“No, sir.  There was no paint on this boot.”

“This is foolery.  I saw it with my own eyes.  It was a broad splash right across the toe.”

The headmaster interposed.

“You must have made a mistake, Mr. Downing.  There is certainly no trace of paint on this boot.  These momentary optical delusions are, I fancy, not uncommon.  Any doctor will tell you——­”

“I had an aunt, sir,” said Psmith chattily, “who was remarkably subject——­”

“It is absurd.  I cannot have been mistaken,” said Mr. Downing.  “I am positively certain the toe of this boot was red when I found it.”

“It is undoubtedly black now, Mr. Downing.”

“A sort of chameleon boot,” murmured Psmith.

The goaded housemaster turned on him.

“What did you say, Smith?”

“Did I speak, sir?” said Psmith, with the start of one coming suddenly out of a trance.

Mr. Downing looked searchingly at him.

“You had better be careful, Smith.”

“Yes, sir.”

“I strongly suspect you of having something to do with this.”

“Really, Mr. Downing,” said the headmaster, “that is surely improbable.  Smith could scarcely have cleaned the boot on his way to my house.  On one occasion I inadvertently spilt some paint on a shoe of my own.  I can assure you that it does not brush off.  It needs a very systematic cleaning before all traces are removed.”

“Exactly, sir,” said Psmith.  “My theory, if I may——?”

“Certainly, Smith.”

Psmith bowed courteously and proceeded.

“My theory, sir, is that Mr. Downing was deceived by the light and shade effects on the toe of the boot.  The afternoon sun, streaming in through the window, must have shone on the boot in such a manner as to give it a momentary and fictitious aspect of redness.  If Mr. Downing recollects, he did not look long at the boot.  The picture on the retina of the eye, consequently, had not time to fade.  I remember thinking myself, at the moment, that the boot appeared to have a certain reddish tint.  The mistake——­”

“Bah!” said Mr. Downing shortly.

“Well, really,” said the headmaster, “it seems to me that that is the only explanation that will square with the facts.  A boot that is really smeared with red paint does not become black of itself in the course of a few minutes.”

“You are very right, sir,” said Psmith with benevolent approval.  “May I go now, sir?  I am in the middle of a singularly impressive passage of Cicero’s speech De Senectute.”

“I am sorry that you should leave your preparation till Sunday, Smith.  It is a habit of which I altogether disapprove.”

“I am reading it, sir,” said Psmith, with simple dignity, “for pleasure.  Shall I take the boot with me, sir?”

“If Mr. Downing does not want it?”

The housemaster passed the fraudulent piece of evidence to Psmith without a word, and the latter, having included both masters in a kindly smile, left the garden.

Pedestrians who had the good fortune to be passing along the road between the housemaster’s house and Mr. Outwood’s at that moment saw what, if they had but known it, was a most unusual sight, the spectacle of Psmith running.  Psmith’s usual mode of progression was a dignified walk.  He believed in the contemplative style rather than the hustling.