“It’s my own key you want,” he said. And then, while he watched her becoming absorbed in the book, involved with its index and plate numbers, a new idea intruded itself.

Rather unwillingly he surveyed it from all sides. He didn’t like it. It was dangerous and perhaps wholly unwise. But it would not go away. It was an idea born of the butterfly key he meant to give her: When he spoke she did not hear—but how if he wrote?

While he still contemplated with dismay this entirely unwelcome and disturbing question, Sabrina took a sheet of note-paper from the top drawer, found a pencil, and began to copy the Papilio page numbers from Kirby’s index. She had only begun when Mrs. Pilton put her head round the door.

“Breakfast’s going in,” she said, and Sabrina thanked her and ran for the stairs.

Alone in the room, he eyed her pencil and paper very thoughtfully indeed. There was plenty of blank space on that page for anything he cared to write there—any message to test this one last means of communication from him to her. He told himself that he dared not try—and yet he took the pencil in his hand. After all, the butter fly boxes had not upset her.

He wondered what to write, and while he wondered the pencil had begun to move, below the page numbers she had copied. You will find my butterfly key—a sort of diary—on the bottom shelf left of the mantelpiece. No more. That would do. That was enough to begin with.

Muffin had been left behind in her flight, and as Hilary laid down the pencil he found the kitten watching him with its innocent blue gaze from the window seat.

“Now we have done it,” he said unhappily, and in sudden panic he would have liked to erase the message entirely or destroy the paper on which he had written it. “It’s asking too much of her. Nobody’s nerves could stand it. I was crazy to try.”

Sabrina was back again remarkably soon, eager for the new game. She went straight to the desk and Kirby’s index to resume her copying. Hilary watched her anxiously. Now for it.

Neatly her figures marched down the paper through his own written lines—and he saw with what he could only acknowledge as blinding relief and thanksgiving that to Sabrina’s tranquil eyes no writing was there but her own.