We returned up the covered way and I was about to close the side door, which Thorndyke had left ajar, when he stopped me.
"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 ?" "No; I didn't hear any sound; which makes me suspect that she did.

She would have heard our voices and she is probably keeping a sharp look-out at this very moment.