What he wanted was a clue. But it is so hard for the novice to tell what is a clue and what isn't. Probably, if he only knew, there were clues lying all over the place, shouting to him to pick them up.
What with the oppressive heat of the day and the fatigue of hard thinking, Mr. Downing was working up for a brainstorm when Fate once more intervened, this time in the shape of Riglett, a junior member of his house.
Riglett slunk up in the shamefaced way peculiar to some boys, even when they have done nothing wrong, and, having "capped" Mr. Downing with the air of one who had been caught in the act of doing something particularly shady, requested that he might be allowed to fetch his bicycle from the shed.
"Your bicycle?" snapped Mr. Downing. Much thinking had made him irritable. "What do you want with your bicycle?"
Riglett shuffled, stood first on his left foot, then on his right, blushed, and finally remarked, as if it were not so much a sound reason as a sort of feeble excuse for the low and blackguardly fact that he wanted his bicycle, that he had got leave for tea that afternoon.
Then Mr. Downing remembered. Riglett had an aunt resident about three miles from the school, whom he was accustomed to visit occasionally on Sunday afternoons during the term.
He felt for his bunch of keys, and made his way to the shed, Riglett shambling behind at an interval of two yards.
Mr. Downing unlocked the door, and there on the floor was the Clue!
A clue that even Doctor Watson could not have overlooked.
Mr. Downing saw it, but did not immediately recognize it for what it was. What he saw at first was not a clue, but just a mess. He had a tidy soul and abhorred messes. And this was a particularly messy mess. The greater part of the flooring in the neighborhood of the door was a sea of red paint. The tin from which it had flowed was lying on its side in the middle of the shed. The air was full of the pungent scent.