It was shortly after nine when they arrived at Derbyshire House, and they went straight to Pamela Overton’s study. The headmistress was dictating letters to her secretary but as soon as she saw them, she stopped and dismissed her. In the four days since Lorna Smith-Couper had died, Pamela Overton had aged visibly. Her face was gray and pale, and there were dark circles beneath her eyes. But her manner was as decisive as ever.

She greeted them in her usual formal manner, and faced them across her desk. “No one here can believe in Miss Callaghan’s guilt. Her arrest is frankly incredible. And it hasn’t stopped the rot, I’m afraid. Already we have lost twenty-one girls and I feel sure others will follow.” She sighed deeply. “But I should not burden you with my problems. That will get us nowhere. How can I help you?”

Lindsay spoke first. “I think Cordelia mentioned that we would like to see the room where it happened. I want to get the scene completely clear in my mind, and it might suggest some possibilities. I take it the police have finished with it now?”

“There will be no problem there,” said Miss Overton. “Their forensic people finished their work there on Monday. The room has, of course, been cleaned and put in order now that they have done with it, but we are not yet using it as a classroom. It’s been locked up to avoid any ghoulishness, but I have the key here. You also want to question some people, don’t you?”

“Yes, we do,” Cordelia replied. “But we’d like to keep it on an informal basis as far as possible, especially where the girls are concerned. It’s mainly a matter of details at the moment. We’d also like to talk to Miss Macdonald, since no one knows the business of the music department better than her. Can you tell us when she’s free today? Also, we’d like a letter from you that we can use as an introduction to people outside the school, saying that we’re inquiring into matters on your behalf and asking for co-operation. And finally . . . we’d like to use Paddy Callaghan’s rooms as our base within the school.”

Pamela Overton moved over to the wall where the timetables were displayed. She studied them for a moment, then told them Margaret Macdonald had one free period later in the morning and another in the afternoon. “If she’s not in her department, try her rooms in Grin Low House,” she explained. She returned to her desk, took a sheet of headed notepaper from a drawer, and wrote a few lines. She handed it to Cordelia, who read,

To whom it may concern; Cordelia Brown and Lindsay Gordon are making inquiries on my behalf regarding the death of Lorna Smith-Couper. I would be grateful if you would give them the fullest co-operation, Yours faithfully, Pamela Overton.