“We’ll have another look at the hall before we go,” said he; and, walking softly before me, he made his way to the front door, where, producing his lamp, he threw a beam of light into the letter-box.

“Any more letters?” I asked.

“Any more!” he repeated. “Look for yourself.”

I stooped and peered through the grille into the lighted interior; and then I uttered an exclamation.

The box was empty.

Thorndyke regarded me with a grim smile. “We have been caught on the hop, Jervis, I suspect,” said he.

“It is queer,” I replied. “I didn’t hear any sound of the opening or closing of the door; did you?”