They had arrived in front of the pavilion backed by trees.  Looking in, Dion saw a lighted lamp.  The slide of jeweled glass had been removed from it.  A white ray fell on an open book laid on a table.

“I was reading here”—­he looked—­“a thing called ‘The Kasidah.’  Sit down!” He pulled the boy down.  “Now what is all this?  Your mother must be in the house.”

“But I tell you she isn’t!”

Dion had sat down between Jimmy and the opening on to the terrace.  It occurred to him that he ought to have induced the boy to sit with his back to the terrace and his face turned towards the room.  It was too late to do that now.

“I tell you she isn’t!” Jimmy repeated, with a sort of almost fierce defiance.

He was staring hard at Dion.  His hair was almost wildly disordered, and his face looked pale and angry in the ray of the lamp.  Dion felt that there was suspicion in his eyes.  Surely those eyes were demanding of him the woman who was hiding among the trees.

“Where have you looked?” he said.

“I tell you I’ve looked everywhere,” said Jimmy, doggedly.

“Did you mother go to bed when you did?”

“No.  I went very early.  I was so infernally sleepy.”

“Where did you leave her?”

“In the drawing-room.  She was playing the piano.  But what’s the good of that?  What time did you come here?”

“I!  Oh, not till very late indeed.”

“Were there any lights showing when you came?”

“Lights!  No!  But it was ever so much too late for that.”

“Did you go on to the terrace by the drawing-room?”

“No.  I came straight up here.  It never occurred to me that any one would be up at such an hour.  Besides, I didn’t want to disturb any one, especially your mother.”

“Well, just now I found the drawing-room window wide open, and mater’s bed hasn’t been touched.  What do you make of that?”

Before Dion could reply the boy abruptly started up.

“I heard something.  I know I did.”

As naturally as he could Dion got between Jimmy and the opening on to the terrace, and, forestalling the boy, looked out.  He saw nothing; he could not have said with truth that any definite sound reached his ears; but he felt that at that exact moment Mrs. Clarke escaped from the terrace, and began to glide down towards the house below.

“There’s nothing!  Come and see for yourself,” he said casually.

Jimmy pushed by him, then stood perfectly still, staring at the darkness and listening intently.

“I don’t hear it now!” he acknowledged gruffly.

“What did you think you heard?”

“I did hear something.  I couldn’t tell you what it was.”

“Have you looked all through the garden?”

“You know I haven’t.  You heard me calling down at the bottom.  You must have, because you answered me.”

“We’d better have a good look now.  Just wait one minute while I put out the lamp.  I’ll put away the book I was reading, too.”