It is the commencement." He tore open the envelope, and drew out a single half-sheet of note-paper.

Across it was scrawled a single sentence only.
"Go back to Lenox." There was no signature, nor any date.

The only noticeable thing about this brief communication was that it was written in yellow pencil of a peculiar shade.

Mr.Sabin's eyes glittered as he read.
"The yellow crayon!" he muttered.
Duson knocked softly at the door.

Mr.Sabin thrust the letter and envelope into his breast coat pocket..