Dr. Cairn closed the manuscript, replaced it and relocked the drawer. He glanced at the clock.
"A quarter past one," he said. "Come, Rob!"
Without hesitation, his son followed him from the house. The car was waiting, and shortly they were speeding through the deserted streets, back to the house where death in a strange guise was beckoning to Myra Duquesne. As the car started—
"Do you know," asked Dr. Cairn, "if Saunderson has bought any orchids—quite recently, I mean?"
"Yes," replied his son dully; "he bought a small parcel only a fortnight ago."
"A fortnight!" cried Dr. Cairn excitedly—"you are sure of that? You mean that the purchase was made since Ferrara—"
"Ceased to visit the house? Yes. Why!—it must have been the very day after!"
Dr. Cairn clearly was labouring under tremendous excitement.
"Where did he buy these orchids?" he asked, evenly.
"From someone who came to the house—someone he had never dealt with before."