"That is the enemy's present line of defence," said he. "It is
the wall of the great Convent of the Madonna. If we can carry it
the city must fall, but they have run countermines all round it,
and the walls are so enormously thick that it would be an immense
labour to breach it with artillery. We happen to know, however,
that the enemy have a considerable store of powder in one of the
lower chambers. If that could be exploded the way would be clear
for us."

"How can it be reached?" I asked.

"I will explain. We have a French agent within the town named
Hubert. This brave man has been in constant communication with
us, and he had promised to explode the magazine. It was to be
done in the early morning, and for two days running we have had a
storming party of a thousand Grenadiers waiting for the breach to
be formed. But there has been no explosion, and for these two
days we have had no communication from Hubert.

The question is, what has become of him?"

"You wish me to go and see?"

"Precisely. Is he ill, or wounded, or dead? Shall we still wait
for him, or shall we attempt the attack elsewhere?

We cannot determine this until we have heard from him. This is a
map of the town, Captain Gerard.