"Who's there?" asked Eustace.
There was no answer.
"Mrs. Prince, is that you?"
"She is up above," said Saunders; "I can hear her walking about the room."
"Then lock the door; bolt it too. Your move, Saunders."
While Saunders sat with his eyes on the chessboard, Eustace walked over to the window and examined the fastenings. He did the same in Saunders's room and the bathroom. There were no doors between the three rooms, or he would have shut and locked them too.
"Now, Saunders," he said, "don't stay all night over your move. I've had time to smoke one cigarette already. It's bad to keep an invalid waiting. There's only one possible thing for you to do. What was that?"
"The ivy blowing against the window. There, it's your move now, Eustace."
"It wasn't the ivy, you idiot. It was someone tapping at the window," and he pulled up the blind. On the outer side of the window, clinging to the sash, was the hand.