“You went to the doctor partly from habit, partly in the muddled and mistaken belief that an authentic prescription would establish the innocence of your purpose. It was carelessness on their part to leave you to get the tablets. Anxiety made you overact, draw attention to your sleeplessness and yourself. However, on the twenty-first of December you went to Vanbrugh Street, to hand them your key. I imagine Mrs. Minelli often had to let you in, so she wouldn’t necessarily conclude that the key was lost, nor ask questions. And on the morning of the twenty-second you made breakfast earlier than usual, putting into your grandmother’s cocoa an extra-large dollop of condensed milk and a crushed dose of sleeping tablets.”

“An overdose, I suppose you mean?” said Majendie.

“Well, yes, but not such a colossal one. A long heavy sleep was the object. You forgot, Ivan, that tough and indestructible as she must have seemed to you, she was an old ill-nourished woman. You saw her to sleep—that’s why you’d had to start early—and went off to work, where for once you forced yourself to your colleagues’ notice, even attached yourself to one of them at lunch. As at the doctor’s, self-consciousness—”

“My dear fellow! Surely an understatement! One would be expecting at any moment a call from the police.”

“Not more than a little. You knew what they were going to do—unfasten the string from round her neck, open the trunk, transfer its contents to their bags, lock it, put the key back on the string and retie. With luck she wouldn’t discover for a day or two that the trunk was empty. And as there was no alarm during the day, you went in the evening to the Vanbrugh. What met you? Long faces and no money. Remember you’d told them in detail what to expect. Remember they were experts. One piece they’d specially looked forward to getting their hands on, a piece they wouldn’t have to break up, for which an unscrupulous private collector would pay thousands. And it wasn’t in the trunk. They said you must have kept it for yourself, or it had never existed. You swore good faith, utter ignorance, amazement, innocence. That didn’t help as regards money, but apparently it convinced them you were speaking the truth. They suggested, I think, that she might for some lunatic reason have taken it out and hidden it about the room, or even in other parts of the house, and that you should go home, give her another dose of tablets and look for it while she slept. You hesitated. They pointed out that if she discovered the robbery before you could find and get rid of the missing object, she’d be able to show it to the police, who’d be far more willing to believe in vanished glories when one of them remained. So you went back to Bright’s.