Marcus Grote had told me there were but two openings to the castle, the Postern and the great gate on the other side of the castle by the donjon keep.

To reach the great gate one must pass out by Cambrai or the Somme Gate and go around the city walls--an hour's journey.
With an air of carelessness I asked Hymbercourt concerning the various entrances to the castle.

He confirmed what Grote had said.

Considering all the facts, I was forced to this conclusion: If the Princess Mary had met the duke at the Postern, Yolanda was not the Princess Mary.
The next day I reconnoitred the premises, and again reached the conclusion that Yolanda could not have met the duke inside the Postern unless she were a witch with wings that could fly thither over the castle walls; ergo, she was not the princess.

With equal certainty she was not a burgher girl.
In seeking an identity that would fit her I groped among many absurd propositions.