“Well, my dear Bunch, it’s hard to say. Of course, right at the very beginning, it did seem as though the ideal person—or rather the obvious person, I should say—to have arranged the hold-up was Miss Blacklock herself. She was the only person who was known to have been in contact with Rudi Scherz, and how much easier to arrange something like that when it’s your own house. The central heating, for instance. No fires—because that would have meant light in the room. But the only person who could have arranged not to have a fire was the mistress of the house herself.

“Not that I thought of all that at the time—it just seemed to me that it was a pity it couldn’t be as simple as that! Oh, no, I was taken in like everyone else, I thought that someone really did want to kill Letitia Blacklock.”

“I think I’d like to get clear first on what really happened,” said Bunch. “Did this Swiss boy recognize her?”

“Yes. He’d worked in—”

She hesitated and looked at Craddock.

“In Dr. Adolf Koch’s clinic in Berne,” said Craddock. “Koch was a world-famous specialist on operations for goitre. Charlotte Blacklock went there to have her goitre removed and Rudi Scherz was one of the orderlies. When he came to England he recognized in the hotel a lady who had been a patient and on the spur of the moment he spoke to her. I dare say he mightn’t have done that if he’d paused to think, because he left the place under a cloud, but that was some time after Charlotte had been there, so she wouldn’t know anything about it.”

“So he never said anything to her about Montreux and his father being a hotel proprietor?”

“Oh, no, she made that up to account for his having spoken to her.”

“It must have been a great shock to her,” said Miss Marple, thoughtfully. “She felt reasonably safe—and then—the almost impossible mischance of somebody turning up who had known her—not as one of the two Miss Blacklocks—she was prepared for that—but definitely as Charlotte Blacklock, a patient who’d been operated on for goitre.