“You’ve got the keys still, haven’t you, Poirot?” I asked, as we reached the door of the locked room.

Taking the keys from Poirot, John unlocked it, and we all passed in. The lawyer went straight to the desk, and John followed him.

“My mother kept most of her important papers in this despatch-case, I believe,” he said.

Poirot drew out the small bunch of keys.

“Permit me. I locked it, out of precaution, this morning.”

“But it’s not locked now.”

“Impossible!”

“See.” And John lifted the lid as he spoke.