John looked puzzled, not quite understanding the portent of this cryptic saying. He handed the two keys which Dr. Bauerstein had given him to me.

“Show Monsieur Poirot everything he wants to see.”

“The rooms are locked?” asked Poirot.

“ Dr. Bauerstein considered it advisable.”

Poirot nodded thoughtfully.

“Then he is very sure. Well, that simplifies matters for us.”

We went up together to the room of the tragedy. For convenience I append a plan of the room and the principal articles of furniture in it.