“This room,” she said to no one in particular, “will become more famous in psychic annals than the home of the Fox sisters at Lilydale.”

Quickly, before she could elaborate on that, Merlini cut in. “Miss Potter doesn’t believe that Rosa Rhys killed Drake. Neither do I. But the psychic force she says is responsible didn’t emanate from another World. It was conjured up out of nothing by someone who was—who had to be—here in this room when Drake died. Someone whom Drake himself asked to be here.”

He moved into the center of the room as he spoke and faced them.

“Drake would never have convinced anyone that Rosa could do what she claimed without a witness. So he gave someone a key—someone who came into this room before Drake and Rosa and Elinor came downstairs.”

The four people watched him without moving—almost, I thought, without breathing.

“That person hid behind that screen and then, after Rosa produced the apports, knocked her out, killed Drake, and left Rosa to face the music.”

“All we have to do,” Merlini went on, “is show who it was that Drake selected as a witness.” He pointed a lean forefinger at Isabelle Potter. “If Drake discovered how Rosa produced the shells and realized she was a fraud, you might have killed him to prevent an exposure and save face for yourself and the Society; and you might have then framed Rosa in revenge for having deceived you. But Drake would never have chosen you. Your testimony wouldn’t have convinced any of the others. No. Drake would have picked one of the skeptics—someone he was certain could never be accused of assisting the medium.”

He faced Elinor. “You said that you accompanied Rosa and your father to the study door and saw them go in alone. We haven’t asked Miss Rhys yet, but I think she’ll confirm it. You couldn’t expect to lie about that and make it stick as long as Rosa could and would contradict you.”

I saw Doran move forward silently, closing in.

“And Paul Kendrick,” Merlini went on, “is the only one of you who has an alibi that does not depend on the sealed room. That leaves the most skeptical one of the three—the man whose testimony would by far carry the greatest weight.

“It leaves you, Dr. Garrett. The man who is so certain that there are no ghosts is the man who conjured one up!”

Merlini played the scene down; he knew that the content of what he said was dramatic enough. But Garret’s voice was even calmer. He shook his head slowly.