The room was empty.
For the first time a real sense of misgiving suddenly took possession of him. He wheeled sharply round, and, hurrying back through the hall, rapped loudly at the door of the study.
"Mr. Carter," he shouted, "are you there?"
There was no answer.
He caught hold of the brass knob, only to make another and still more ominous discovery. Somebody had turned the key from inside.
With a quick breath he stepped back a couple of paces, and then, hunching up his shoulder, hurled himself against the panel. Under the impact of twelve stone and a few odd pounds the lock gave with a splintering crash which echoed through the house. The door swung open, and at the same moment the shrill scream of a terrified woman rang out from the top landing.
Clutching the broken woodwork to steady himself, Colin fumbled for the switch. His fingers closed on it in the darkness and, half prepared as he was for some horror, an involuntary cry broke from his lips as the whole room flared suddenly into light.
Face upward, in the centre of the French windows, lay the huddled figure of the Professor. One arm was twisted under him, and his white hair was dabbled in a stream of blood which still oozed slowly from a gaping wound in his forehead.