The Closes lived in a splendid big house in the Murray Hill section.  The presentation of the note quickly brought Mrs. Close’s maid down to us.  She had not gone to the hospital because Mrs. Close had considered the services of the trained nurses quite sufficient.

Yes, the maid had noticed how her mistress had been failing, had noticed it long ago, in fact almost at the time when she had begun the X-ray treatment.  She had seemed to improve once when she went away for a few days, but that was at the start, and directly after her return she grew worse again, until she was no longer herself.

“Did Dr. Gregory, the X-ray specialist, ever attend Mrs. Close at her home, in her room?” asked Craig.

“Yes, once, twice, he call, but he do no good,” she said with her French accent.

“Did Mrs. Close have other callers?”

“But, m’sieur, everyone in society has many.  What does m’sieur mean?”

“Frequent callers—­a Mr. Lawrence, for instance?”

“Oh, yes, Mr. Lawrence frequently.”

“When Mr. Close was at home?”

“Yes, on business and on business, too, when he was not at home.  He is the attorney, m’sieur.”

“How did Mrs. Close receive him?”

“He is the attorney, m’sieur,” Marie repeated persistently.

“And he, did he always call on business?”

“Oh, yes, always on business, but—­well, madame, she was a very beautiful woman.  Perhaps he like beautiful women—­eh bien? That was before the Doctor Gregory treated madame.  After the doctor treated madame M’sieur Lawrence do not call so often.  That’s all.”

“Are you thoroughly devoted to Mrs. Close?  Would you do a favor for her?” asked Craig pointblank.

“Sir, I would give my life, almost, for madame.  She was always so good to me.”

“I don’t ask you to give your life for her, Marie,” said Craig, “but you can do her a great service, a very great service.”

“I will do it.”

“To-night,” said Craig.  “I want you to sleep in Mrs. Close’s room.  You can do so, for I know that Mr. Close is living at the St. Francis Club until his wife returns from the sanitarium.  To-morrow morning come to my laboratory”—­Craig handed her his card—­“and I will tell you what to do next.  By the way, don’t say anything to anyone in the house about it, and keep a sharp watch on the actions of any of the servants who may go into Mrs. Close’s room.”

“Well,” said Craig, “there is nothing more to be done immediately.”  We had once more regained the street and were walking up-town.  We walked in silence for several blocks.

“Yes,” mused Craig, “there is something you can do, after all, Walter.  I would like you to look up Gregory and Close and Lawrence.  I already know something about them.  But you can find out a good deal with your newspaper connections.  I would like to have every bit of scandal that has ever been connected with them, or with Mrs. Close, or,” he added significantly, “with any other woman.  It isn’t necessary to say that not a breath of it must be published—­yet.”