“Well, you ought to know,” Alleyn remarked lightly, and went out smiling to himself.

At Catherine Street he was received by Nash, who stared like a boiled owl at the inspector. Nash, who carried in his head a sort of social ladder, had quietly decided that police officers of all ranks were to be graded with piano-tuners. Chief Detective-Inspector Alleyn did not conform, in appearance or in manner, to this classification. Nash performed a reluctant mental somersault.

“Lady O’Callaghan?” asked Alleyn.

“Her ladyship is expecting you, sir.” Alleyn gave him his hat and overcoat. Nash said: “Thank you, sir,” and waddled off towards the study. Alleyn followed him. Nash opened the door.

“Mr. Alleyn, m’lady,” he said. Obviously the degrading titles were better omitted.

Alleyn walked in.

Cicely O’Callaghan sat before the fire in her husband’s arm-chair. As Alleyn came in she rose to her feet and looked serenely at him.

“How do you do?” she said.

“How do you do? I am extremely sorry to bother you, Lady O’Callaghan.”

He thought: “Golly, she is like Ratsbane!”

“But I wished to see you. It is good of you to come so promptly.”

“Not a bit.” This was an exceedingly polite introduction to a murder story.

“Do sit down. I suppose the man who came here this afternoon has told you my reason for communicating with the police?”

“I believe Inspector Fox gave me a full account of your conversation.”

“Yes. I am convinced that my husband was murdered— probably poisoned.”

“I am sorry that in addition to your grief you should suffer the pain occasioned by such a suspicion,” said Alleyn and wondered how long they were to make speeches at each other.

“Thank you. Do you agree with me that the circumstances warrant an inquest?”

“I think I should like to hear a little more about them. I have read the letters.”

“Surely they, in themselves, are enough to arouse anybody’s suspicion?”

“Lady O’Callaghan, it is extremely unusual for a person contemplating homicide to write such letters. I do not say it is unknown, but it is very unusual. I expect Fox told you that.”

“I believe he said something of the sort. My point is this: I do not think the murderer contemplated homicide when writing the letter. I do think that a person capable of writing such a letter would also be capable of seizing the opportunity when it presented itself.”

“So it is Phillips and the girl she’s after,” thought Alleyn.

“I see your point, of course,” he said slowly.