Miss Silver went on.

“I see that you are inclined to agree with me. I am very glad of that, for I need your help. The murderer is a cunning and dangerous person and is still at large. The matter is extremely urgent, and the greatest care and discretion must be exercised if a further fataility is to be avoided.”

Ella Jackson said “Oh!” on a sharp breath of protest.

Miss Silver shook her head.

“I am not exaggerating. I am very deeply concerned. Chief Inspector Lamb is an able and honest man-I have a great respect for him-but I cannot shake his conviction that Miss Garside committed suicide, and that this suicide closes the case. I must have evidence in order to shake this conviction. Enquiries which I shall make tomorrow will, I hope, provide me with some of this evidence. Meanwhile it is in your power to help me. Will you do so?”

Ella Jackson said, “Yes, I will.”

Miss Silver beamed upon her.

“That is so very kind. I will not keep you any longer than I can help. I have a question to ask you, and I hope very much that you will be able to answer it. Your sister talked to you about her affairs, did she not?”

“About some of them. She didn’t tell me everything.”

“Did she tell you that she was being blackmailed?”

Ella Jackson took a quick, short breath.

“How did you know?”

“Another person in the house was being blackmailed. Miss Roland was in possession of a letter from this person to the blackmailer. The police regard this as evidence that your sister was herself the blackmailer, but from the fact that she exposed this letter carelessly in her bag and allowed the writer to see it I deduce that she was not a principal in the matter. I believe she merely intended to tease the writer of the letter. I began to wonder whether she herself was being blackmailed, and had come into possession of the letter in an attempt to secure evidence against the blackmailer. If she knew who this person was, it would supply a motive for the murder. Now, Mrs. Jackson- can you help me?”

Ella Jackson leaned forward.

“She was being blackmailed-she told me that-and she came down here because she thought she’d got a clue to the person who was blackmailing her. She thought it was someone in Vandeleur House-that’s why she took that flat. Of course it suited her in other ways-it was out of the way and quiet, and she wanted to be near me-but that’s really why she took it. There was a girl she’d known when she was on the halls-a girl that used to be an acrobat but she had an accident and couldn’t carry on. Carrie got her to go into service with Mrs. Underwood in No. 3 so that she could help her. The last thing she told me was that they were getting on fine and going to make someone sit up.”

“She didn’t tell you who it was?”

Ella shook her head.

“I didn’t ask her. To tell you the truth, Miss Silver, I didn’t like the sound of it. The fact is she’d got the idea she could turn the tables-get hold of something that would put this blackmailer in the wrong, and use it to make them give up trying to blackmail her. I didn’t like the sound of it at all. It seemed right down dangerous to me, and so I told her.”

“You were right. She tried to blackmail the blackmailer, and she got the worst of it. That was inevitable. She was dealing with a dangerous and experienced criminal. We still have that criminal to deal with. She gave you no clue as to the person’s identity?”

Ella shook her head.

“Not even by the use of a pronoun? She never said he or she?”

Ella shook her head again.

“No, it was always they. ‘They think they can do this or that, but I’ll show them’-you know how one talks. It isn’t grammar, but everyone does it.”

Miss Silver nodded in an abstracted manner. Her thoughts were busy. After a little she said,

“Mrs. Jackson, will you tell me why your sister was being blackmailed?”

Ella started and flushed. Then she said,

“Oh, well, I suppose it doesn’t matter now. You get past minding, don’t you? And it wasn’t her fault, poor Carrie-she thought he was dead.”

“Bigamy?” said Miss Silver.

Ella flushed again.

“She thought he was dead. She married him when she was only a kid-ran away from home. They were on the halls together. He was a horrid man. Well, in the end he went off with someone else, and she heard he was dead. I suppose she ought to have taken more trouble about finding out if it was true, but she didn’t bother. Only after she’d married Jack Armitage and he’d been killed the blackmail began. She paid up once or twice because she was afraid that if Major Armitage found out he’d stop the allowance, and she was getting friendly with the gentleman she was going to marry, Mr. Maundersley-Smith-she didn’t want him to know. He was the sort that thinks a girl’s perfect because she’s pretty. I always thought he’d have some shocks if he married Carrie. But there-it never came to that, only you can see why she didn’t want him to know.”

Miss Silver said, “Yes, indeed.” She though Ella Jackson a very sensible young woman. Fond of her sister too, but not blind to her faults. She coughed and enquired,

“Was she being asked for money all the time, or only at first?”

Mrs. Jackson had a startled look.

“She hadn’t a lot to give,” she said.

“She had some valuable jewellery.”

“Well, nearly all of it came from Mr. Maundersley-Smith- everything except the diamond ring that Jack Armitage gave her. Mr. Smith would have noticed if she hadn’t worn his presents. Besides she looked upon the jewellery as a kind of nest-egg.”

“Then it wasn’t money she was asked for?”

The startled look was still there. Ella said,

“No-it wasn’t.”

“I think I can guess what it was. Mr. Maundersley-Smith is a big man in the shipping world. It might have been supposed that your sister would be able to supply valuable information.”

Ella nodded.

“Yes-that was it. And it fairly got her back up. Carrie was my sister, and no one knows her better than me. She’d done a lot of things I didn’t like-it’s no good pretending she hadn’t- but that’s a thing she wouldn’t do, not with a war on anyhow. So she set herself to find out who was running the show, and to get even with them.”

“A very dangerous enterprise,” said Miss Silver gravely.

The night passed without incident. A young police constable kept solitary vigil on the landing between No. 3 and No. 4. Miss Silver remained at No. 3. A comfortable bed was made up for her on the drawing-room sofa, but she did not occupy it. As soon as the rest of the household had retired and might be supposed to be asleep, she carried a chair to the kitchen and sat there all night with the door wide open to the hall of the flat. At intervals she went to the window and looked out, raising the sash so that she could see right along that side of the house. The window of Ivy’s small bedroom was so near that she could have touched it with her hand. She observed with approval that it was closely fastened, and that the curtains were drawn across it on the inside. She could also have touched the ledge which ran all round the house beneath the windows. There was a similar ledge on every floor. She wondered how often Ivy Lord had passed along this one. She meant to make quite certain that neither she nor anyone else should pass along it tonight. The night went slowly by.

As soon as it was light she took a bath-the hot water supply was really most commendable. She dressed herself in her outdoor clothes, partook of a cup of cocoa and a bowl of bread and milk, and went into Mrs. Underwood’s room to inform her that she would be away for some hours and not to wait tea, though she hoped to be back by then. After which she walked downstairs, bade Bell a cheerful good-morning, and departed upon her errand.