Now, thought Fandor, I must be just above the Dépôt! And now to find out how Jacques Dollon, dead or living, has got out of here! No use thinking of a window, for the cell has not got one... Fuselier has reason on his side when he declares that you do not get out of the cells of the Dépôt, nor out of the Palais!

Well now – to carry off Dollon, dead or living, by way of the Palais Square, or by the boulevard, is out of the question: there are too many people about!... To carry him off by one of the exits, on to either of the quays, is equally out of the question: there are the sentries in the first place, and then comes the Seine – then Jacques Dollon has left the Dépôt, or he has not, or, at any rate, he is still somewhere in the Palais – unless...

Fandor interrupted his musings to light a cigarette: smoking helped him to think things out:

It is equally certain that if Dollon is still in the Palais, he cannot be in the Dépôt, for the Dépôt has been rigorously searched since his disappearance, and he would most certainly have been found, had he been anywhere about the place. It is also certain that he is not inside the Palais, because the only means of communication between the Dépôt and the Palais is a single staircase, and it is certain that a corpse could not have been taken that way unnoticed.... Then it follows that Jacques Dollon must have got out by the only ways which are in communication with the Dépôt – that is to say, the drains and the chimneys...

How could he have got out, or been got out by the drains? As far as I know, there is no system of pipes large enough to allow the passage of a man through the pipes which join the main sewers; but, as a set-off to that, there is a chimney – the ancient chimney of Marie Antoinette – which communicates with the Dépôt, and the roof I am now on: it must have been by this chimney that the escape was made! Let us see whether this is so or not...

By the light of his tiny dark lantern Fandor studied afresh the plan of the Palais, and tried to identify the various chimneys about him. He soon picked out the mouth of Marie Antoinette’s chimney. After a considering glance at it, he remarked”

“That’s odd! Here is the only chimney whose opening is below the ledge of the roofs! It is certain that unless one had been warned, and had examined this roof from some neighbouring building, the mouth of this chimney would not be noticed. If Jacques Dollon passed out by it, no one would notice his exit!”