The three of you leap down into the hole, to find that the rubble has made a mound below. You bang your hands and knees on some timbers and stone rubble, but experience no damage. The rat's torch reveals a masonry tunnel that has been made a very long time ago, the floor of which is about 15 feet below the surface.
If you're with the rat, you're running now, along the tunnel. "This will take us under the nearest hill, towards the east. From there you'll be able to climb up a series of tunnels and stairs until you find an exit in the forest. Once you do, go north along the ridge, until you reach the sea; you'll see a beach there. I will do my best to send your horse there. The soldiers will probably seize the horse for a time, but when they search for you my rats will cause the horse to flee; they'll herd the horse towards that beach. It should be there by sunrise."
You take a series of left and right turns, passing other tunnels, for about fifteen rounds, before reaching a flight of stairs up. "I must go back for my friends," says the rat. "Just keep climbing. Don't take any steps that go down. You may get lost, but so long as you climb you'll find your way out."