Against the Orcs

From the introduction: The orc uprising around Nirzumbil must come to an end! The Mercur trade coster is benefiting too much from the blockade of the dwarven stronghold and threatens to corner the market on iron ore and gems for years to come. If the orc warlord commanding the armies can be slain, the orc forces will surely fall apart. But how to find and kill a warlord who is powerful enough to unite thousands of orcs? A multi-session adventure for four or five 6th level characters