locked door. There were no secret doors - the police have
looked at every centimetre of the floor, the ceiling, and the
walls. And I also looked very carefully. So, no secret doors.
What about the chimney? It is wide enough for a body for
three metres, but higher up it is much narrower. Not even
a cat could climb through it to the top. So what is left?'
'The two windows,' I said. 'But they were fastened on
the inside, weren't they?'
'Yes, and no,' said Dupin. 'Let me explain. We can see
all of the window on the left, you remember, but only the
top half of the window on the right, because the head of
the bed is pushed up next to the window. The police tried
to open the window on the left, but found a very strong
nail in the wood, which stopped the window opening.