“Where you going?” Graham asked sharply.

Paredes waved his hand indifferently and walked on up.  There was something of stealth in his failure to reply, in his cat-like tread on the stairs.  Graham and Bobby stared after him, unable to meet this new situation audibly because of Groom.  Yet five minutes had gone.  There was no time to be lost.  Paredes mustn’t rob Bobby of his chance.  With a sort of desperation he started for the stairs.  Graham held out his hand as if to restrain him, then nodded.  Bobby had his foot on the first step when Katherine’s cry reached them, shaping the moment to their use.  For there was no fright in her cry.  It was, rather, angry.  And Bobby and Graham ran up while Doctor Groom remained in his chair, an expression of blank amazement on his face.

A candle burned on the table in the upper hall.  Katherine and Paredes stood near the entrance of the old corridor.  Paredes, as usual, was quite unruffled.  Katherine’s attitude was defensive.  She seemed to hold the corridor against him.  The anger of her cry was active in her eyes.  Paredes laughed lightly.

“Sorry to have given the household one more shock.  Fortunately no harm done.”

“What is it, Katherine?” Graham demanded.

“I don’t know,” she answered.  “He startled me.  He entered the corridor.”

Paredes nodded.

“Quite right.  She was there.  I was on my way to my room.  If your house had electricity, Bobby, this incident would have been avoided.  I saw something dark in the corridor.”

“You may not know,” Graham said, “that ever since we found Howells, one of us has tried, more or less, to keep the entrance of that room under observation.”

“Yet you were all downstairs a little while ago,” Paredes yawned.  “It’s too bad.  I might have taken my turn then.  At any rate, since I was excluded from your confidence, I overcame my natural fear, and, for Bobby’s sake, slipped in, and, I am afraid, startled Miss Katherine.”

“Yes,” she said.

His explanation was reasonable.  There was nothing more to be said, but Bobby’s doubt of his friend, sown by Graham and stimulated by the incidents of the last hour, was materially strengthened.  He felt a sharp fear of Paredes.  Such reserve, such concealment of emotion, was scarcely human.

“If,” Graham was saying, “you really want to help Bobby, there is something you can do.  Will you come downstairs with me for a moment?  I’d like to suggest one or two things before the police arrive.”

Without hesitation Paredes followed Graham down the stairs.

Katherine turned immediately to Bobby, her eyes eager, full of the tense determination that had dictated her plan in the library.

“Now, Bobby!” she whispered.  “And there’s no time to waste.  They may be here any minute.  I won’t see you go, but I’ll be back at once to guard you against Paredes if he slips up again.”