Willard followed instructions and then looked inquiringly across the few feet of shining mahogany and green blotting pad to the countenance of the Principal. This was his first close view of Doctor McPherson, although he had seen him at least once every day. Usually the length of the assembly hall separated them, and just now Willard wished mightily that it still separated them. Not that the Doctor looked very formidable, for he didn’t. He wasn’t a large man, and his strength and vigor were evidently that of the mind rather than of the body. His brown eyes, rather golden brown, were soft and kindly, and two deep creases that led from the corners of his short, straight nose to the ends of his rather wide mouth suggested that he preferred smiling to frowning. Even now there was a smile on the Doctor’s face, although it wasn’t a smile that encouraged the caller to emulate it. “I presume,” said the Doctor, “that you know why I sent for you, Harmon.” “No, sir,” answered Willard, honestly enough. “Really?” The Doctor’s grizzled brows went up in faint surprise. Leisurely, he swung his chair a little and opened the upper left-hand drawer beside him. Then he laid something midway between him and Willard, something that by its appearance seemed to desecrate the immaculateness of the mahogany on which it rested. It was a crumpled object, white in places, black in other places, smeared and stiffened. In brief, it was a white handkerchief befouled with black paint. “Have you ever seen that before, Harmon?” asked the Doctor. CHAPTER XXI BOB SAYS SO Willard’s heart sank. There was no need to pick the thing up for closer examination. Its crumpled, distasteful folds showed one border missing, and, if evidence had still been lacking, closer inspection would have elicited the fact that, half obliterated by a paint smudge, the word “Harmon” was plainly printed on a corner. It was the handkerchief that he had given to Bob Newhall Saturday night to wipe his hands on. “Yes, sir,” replied Willard. “When and where?” asked the Doctor quietly. “Last Saturday night, sir, at Hillsport.” The Doctor picked the object up gingerly and dropped it back in the drawer. Then he closed the drawer slowly and gazed thoughtfully for a short moment at the book he had laid aside. “I have received a very indignant letter from Doctor Handley, at Hillsport School,” he said presently. “He tells me that some time during Saturday night the wall of his residence was defaced with black paint in--um--in ill-advised celebration of Alton’s football victory over Hillsport.” Willard gasped. “We--I didn’t know it was his wall, sir!” he exclaimed. “Is that true? You didn’t know that Doctor Handley’s residence stood at the corner, across from the school entrance?” “No, sir,” answered the boy earnestly. “I’d never been there before, sir.” “But the others? They must have known.” “The others?” stammered Willard. “Yes,” replied the Doctor gently. “You said ‘we’ a moment ago.”