One morning he interrupted her in the midst of her customary tirade. “By the way,” he said in his soft, melancholy voice, “I suppose it was really you who poisoned Mrs. Hutton.”

Miss Spence stared at him for two or three seconds with enormous eyes, and then quietly said, “Yes.” After that she started to cry.

“In the coffee, I suppose.”

She seemed to nod assent. Dr. Libbard took out his fountain-pen, and in his neat, meticulous calligraphy wrote out a prescription for a sleeping draught.