Overturned Paddy Wagon

From the introduction:

Hidden from the world at large by the trees shielding the road from view a paddy wagon used to transfer prisoners between prisons, from and to court, or to the hangman's gallows has been ambushed. Trying to escape the attackers at break neck speeds one of the wagon's wheels finally gave out and the cart crashed. Parts of it are strewn about the road and its horses have run off. Still, constructed from arm thick wooden beams and equally sturdy boards the wagon has remained largely intact. Especially its cell seems undamaged.