The detective nodded.  “Much obliged,” he said, with a grin.  He ran lightly into the alcove and tiptoed out of the terrace door, closing the door behind him.  Beresford and Billy departed to take up their posts in the kitchen.  “I’ll go with you, if you don’t mind—­” and Jack Bailey had followed them, leaving Miss Cornelia and Dale alone with the Doctor.  Miss Cornelia, glad of the opportunity to get the Doctor’s theories on the mystery without Anderson’s interference, started to question him at once.

“Doctor.”

“Yes.”  The Doctor turned, politely.

“Have you any theory about this occurrence to-night?” She watched him eagerly as she asked the question.

He made a gesture of bafflement.

“None whatever—­it’s beyond me,” he confessed.

“And yet you warned me to leave this house,” said Miss Cornelia cannily.  “You didn’t have any reason to believe that the situation was even as serious as it has proved to be?”

“I did the perfectly obvious thing when I warned you,” said the Doctor easily.  “Those letters made a distinct threat.”

Miss Cornelia could not deny the truth in his words.  And yet she felt decidedly unsatisfied with the way things were progressing.

“You said Fleming had probably been shot from above?” she queried, thinking hard.

The Doctor nodded.  “Yes.”

“Have you a pocket-flash, Doctor?” she asked him suddenly.

“Why—­yes—­” The Doctor did not seem to perceive the significance of the query.  “A flashlight is more important to a country Doctor than—­castor oil,” he added, with a little smile.

Miss Cornelia decided upon an experiment.  She turned to Dale.

“Dale, you said you saw a white light shining down from above?”

“Yes,” said Dale in a minor voice.

Miss Cornelia rose.

“May I borrow your flashlight, Doctor?  Now that fool detective is out of the way,” she continued some what acidly, “I want to do something.”

The Doctor gave her his flashlight with a stare of bewilderment.  She took it and moved into the alcove.

“Doctor, I shall ask you to stand at the foot of the small staircase, facing up.”

“Now?” queried the Doctor with some reluctance.

“Now, please.”

The Doctor slowly followed her into the alcove and took up the position she assigned him at the foot of the stairs.

“Now, Dale,” said Miss Cornelia briskly, “when I give the word, you put out the lights here—­and then tell me when I have reached the point on the staircase from which the flashlight seemed to come.  All ready?”

Two silent nods gave assent.  Miss Cornelia left the room to seek the second floor by the main staircase and then slowly return by the alcove stairs, her flashlight poised, in her reconstruction of the events of the crime.  At the foot of the alcove stairs the Doctor waited uneasily for her arrival.  He glanced up the stairs —­were those her footsteps now?  He peered more closely into the darkness.