“Mademoiselle, it is of no importance what I think. What did you do when you got back to the house?”

“I went up to my room.”

“And stayed there until when?”

“Until about ten o’clock.”

“Is there anyone who can prove that?”

“Prove? That I was in my room, you mean? Oh! no. But surely⁠—oh! I see, they might think⁠—they might think⁠—”

I saw the dawning horror in her eyes.

Poirot finished the sentence for her. “That it was you who entered by the window and stabbed Mr. Ackroyd as he sat in his chair? Yes, they might think just that.”