You can put him ashore a mile or two along the coast.
"Now as to the escape, monsieur.

Here is a sharp saw.

With it you can cut round the lock of your door.

There are two outside bolts, whose position I dare say you have noticed; by cutting a hole close to each of them, you can get your hand through and draw them.

Here is a short-handled augur, to make a hole for the saw to go through.
"There are four sentries at night, in the courtyard.