that Walter was ill and that I had better not come."
"Oh!" This statement took the inspector aback. If Fane had been ill at Westcliff-on-Sea, he certainly could not be the man met by Mulligan. "Can you show me the wire?" he asked.
"I will send it round to you. And I am quite sure that when you see Mr. Fane you will not suspect him of this crime. A better and more kindly man does not live. However this woman came to enter the house, however she was killed, and for what reason, Mr. Fane can know nothing of the matter. How was she killed?"
"Stabbed under the left shoulder-blade while she was singing."
"Singing! What was she singing, and why in a strange house?"
"She was singing 'Kathleen Mavourneen.'"
Laura looked surprised. "My sister's favourite song."
"Oh indeed," said Derrick sharply. He hesitated. "Your sister is also at Westcliff-on-Sea?"
"Are you about to accuse her?" asked Laura disdainfully.
"I accuse no one," replied Derrick, nettled. "I am only trying in all directions to learn facts upon which to build up a theory."
"Then why don't you look for real evidence?"
"Such as what, Miss Mason?"
"Such as the weapon with which this woman was killed."
"We have looked. It cannot be found. The murderer took it away. He would not be such a fool as to leave that lying about. The doctor fancies from the nature of the wound that it must be a long slim dagger-a kind of stiletto."
"Such as a foreigner might use," said Laura involuntarily.
"What do you mean?" asked the inspector sharply.
Laura flushed. "Nothing, nothing," she responded; "but foreigners usually make use of such a weapon, don't they? An Englishman would not kill a person with a stiletto."
"It's not British, certainly," said Derrick, with insular prejudice; "but a woman might use such a thing. Still, we do not know that the assassin is a man or" – he looked straight at her-"a woman."
Laura could not quite understand his meaning, since it never struck her that he meant to incriminate her in the matter. She took no notice, being anxious to learn what Derrick thought. "What is your theory on existing facts?" she asked coldly.
Derrick reflected. "I hardly know what to say. Let us suppose that the woman admitted herself into the house. How she got the latch-key I am not prepared to say. She came to meet some one-possibly the two people who killed her."
"The two people?" interrupted Laura abruptly.
"There was the young man who kept Mulligan in talk," explained the officer, "and the one who presumably killed her. Let us suppose, for the sake of argument, that this woman met these two men. Seeing a policeman at the gate, Number One goes out to lure him away. Left alone with Number Two, the woman sits at the piano to sing. On the music-stand is 'Kathleen Mavourneen.' She knows that song and sings it. The assassin, standing behind her, watches his opportunity and stabs her. Then he goes."
"You forget that the song was being sung, according to your own account, before Number One left the gate with the policeman."
"Certainly. But the woman might have begun to sing immediately after Number One left."
"Before," insisted Laura. "The policeman listened while Number One was in the room. It was the song that made him stop. I am only going by what you told me. Your theory doesn't fit together."
Derrick frowned. "It is hard to put the pieces of the puzzle together, Miss Mason. Only in detective fiction does the heaven-born genius put this and that together in a flash. I-a mere mortal-am groping in the dark. I may discuss a hundred theories before I hit on the right solution. Nothing more can be done till I see Mr. Fane. As the woman was in his house, he must know-"
"He knows nothing," interrupted Laura imperiously; "he can't know. The man is ill at the seaside and-"
Derrick interrupted in his turn. "I'll wait till I hear what Mr. Fane has to say," he declared abruptly.
He rose to terminate the interview. As he opened the door Tracey entered hurriedly. "My car's found," he burst out.
"Where?" asked Derrick and Laura together.
"Stranded in the yard of Charing Cross Station."
Laura turned quickly on Derrick. "I beg you to observe, Mr. Inspector, that you cannot get to Westcliff-on-Sea from Charing Cross."
"I have not yet accused Mr. Fane," retorted the inspector.
CHAPTER V
PUBLIC OPINION
Naturally there was great excitement over "The White Room Crime," as it soon came to be called. The inhabitants of Troy were shocked, as such a thing had never before happened in their locality. They found their holy quiet invaded by a host of reporters, detectives, policemen, idlers, and morbid folk who wished for new sensations. Mr. and Mrs. Fane left their child at the seaside and came up for the inquest, which was held at a quiet public-house in the neighbourhood. Fane insisted that the body should be taken away from Ajax Villa.
"It should have been removed at once," he declared. "I don't know the woman. I never set eyes on her. My wife doesn't know her, and I can't conceive how she came to die in my place."
"Do you alone own the latch-key?"
It was Derrick who asked this question, and he eyed Fane sharply as the reply came.
"I alone own the latch-key of my house," said Fane; "it is a peculiar lock. No other key but mine will fit it. See!" He produced a long slim key, upon which Derrick, unlocking a drawer, took out of it the key picked up by Mulligan. The two were identical in all respects. "You see," said Derrick in his turn, "a duplicate has been made. I noticed that the strange key was new when Mulligan showed it."
"Where did you get this key?"
"The young man who lured Mulligan away from the gate dropped it."
"Very strange," said Fane in a puzzled tone. "I can't understand. I don't think the locksmith who made me my key can have made two, as I especially agreed with him that he was not to do so."
"Have you his address?"
"Yes. It is at my office in the city. I will give it to you. But I am sure the man is to be trusted. A most respectable tradesman."
"Hum," said Derrick, scratching his chin. "Respectable tradesmen do queer things for money at times."
"But why should this strange woman have been brought to this house-my house-to be murdered?"
"I can't say. That is what we have to find out. You don't know this woman?" asked Derrick doubtfully.
Fane was a smart, cheery-faced fellow with rather a weak mouth. He looked rather haggard, as he had practically risen from a sick-bed to obey the summons of the law. For the moment he appeared puzzled when Derrick spoke. Then he flashed an indignant look on him, and grew red. "Do you mean to insinuate that I did something underhand, Mr. Inspector?" he inquired excitedly.
"Men admire pretty women,"
