You come to a place where the castle's corridors split into two
directions. If you go to your right, you should get to the front gate
of the castle, which may be blocked by guards. If you go to your
left, you might be able to sneak out of the palace's secret back
entrance, though you will hve to journey through several open
courtyards to reach it.
You speed away from the guards and run to the wall behind you. You
jump up on top of it, not stopping to think before you jump onto the
other side and begin to run furiously through the castle.