whether they were all there. Suddenly he stopped.

"Yes," he exclaimed excitedly, "one of them is gone." Nervously he
fumbled through them again. "One is gone," he repeated, looking at
us, startled.

"What was it about?" asked Craig.

"It was a note from an artist, Thurston, who gave the address of Mrs.
Boncour's bungalow - ah, I see you have heard of him. He asked
Dixon's recommendation of a certain patent headache medicine. I
thought it possibly evidential, and I asked Dixon about it. He
explained it by saying that he did not have a copy of his reply, but
as near as he could recall, he wrote that the compound would not
cure a headache except at the expense of reducing heart action
dangerously. He says he sent no prescription. Indeed, he thought
it a scheme to extract advice without incurring the charge for an
office call and answered it only because he thought Vera had become
reconciled to Thurston again. I can't find that letter of Thurston's.
It is gone."

We looked at each other in amazement.

"Why, if Dixon contemplated anything against Miss Lytton, should he
preserve this letter from her?" mused Kennedy. "Why didn't he
destroy it?"

"That's what puzzles me," remarked Leland. "Do you suppose some
one has broken in and substituted this Lytton letter for the
Thurston letter?