Lindsay grinned, then said thoughtfully, “Yet whoever it was must have done just that. There were so many people flitting around it must have been an extremely dodgy exercise. It’s hard to believe anyone could have got away with it completely unseen. Oh, and by the way, you’ve just fallen into the oldest trap. You said you have the evidence of your eyes that she didn’t budge from the hall. But don’t forget that you were out of the hall yourself during the crucial period. All you can say is that she was there when you left and there when you returned. For all you know, she could have slipped out, just like you did.”

“Except that, by my own admission of where I was, we would have bumped smack into each other on the doorstep.”

“Unless one of you was actually in there committing murder.” Lindsay stopped on the stairs. “Now what am I saying? Oh God, I’m sorry, Cordelia. It’s just my love of perversity . . . Look, I know it wasn’t you. And I know it wasn’t Pamela Overton, because I do have the evidence of my own eyes to go on there. Forgive my crassness.”

Cordelia stood a couple of steps above her, smiling “Nothing to forgive. I don’t expect two nights of passion to convince you that I’m above suspicion.”

They were suddenly grinning at each other like schoolkids who have just discovered that they are best friends. Together they ran up the few remaining stairs. Only the sight of the music room door sobered them into rather frightened adults again. Cordelia put the key in the lock, then paused. “Ready?”

Lindsay nodded. Cordelia turned the key and opened the door. It swung open silently to reveal a completely ordinary music classroom. It smelled faintly of a mixture of polish, chalk, and resin. In one corner was a neat stack of music stands. On open shelves along one wall were piles of sheet music. Glass-fronted cupboards beneath the shelves revealed boxes of strings, reeds, percussion instruments, and piles of blank manuscript paper. There were about twenty chairs scattered around. At the far end of the room was a baby grand piano, the teacher’s desk on a raised dais in front of the blackboard, and a walk-in cupboard whose open door revealed neatly ordered string instruments in racks; violins, violas, cellos, even a mandolin and two guitars.