Complex sentence: Due to a broken carriage wheel, the group are four hours late and are dumped unceremoniously just about two kilometres from Carlsbad (their fear-stricken coach driver refuses to continue any further as night is falling), near the castle.
Split into simpler sentences: Due to a broken carriage wheel, the group are four hours behind schedule. As night draws near, their fear-stricken coach driver refuses to continue any further and dumps them unceremoniously just about two kilometres from Carlsbad and within sight of the castle.