Although they do not know its purpose, they suspect that it may be a lesser daemon of the Chaos Powers, trapped in the rocks below the earth in ages past, and freed by the incessant digging of the Goblins and Orcs as they search for the lost treasure of the Dwarfs who once inhabited the city. The truth is that the daemon has escaped the prison of rock that held it for so long, and is now resident in a statue of a great fire dragon in an ancient temple (the firechasm). Soon it will fully awaken, and walk the world once more. The Wizards have employed the Warriors to destroy the daemon and ensure that this never happens.
However, before they were ever employed to destroy the daemon, our plucky band of adventurers had already had an adventure together, if you can call it that. On their first adventure together, they were headed for a Tomb Chamber to perform an exorcism.
After an incredibly successful adventure, the party of warriors had a fairly disastrous trip to civilization. On their way to town, the each lost a treasure, and in addition the Dwarf lost the magic sword he hadn't needed to use on the daemon statue, and the Wizard lost the Elf healing potion he had started the adventure with. This meant the Wizard quickly went from having three drinks of potion that could completely cure all wounds, to having zero.
On reaching the village, the Barbarian sold the useless Bow of Loren, splitting the gold equally amongst the warriors. He then lost his Ensorcelled Blade, the last remaining treasure from the entire adventure, in a game of chance. He did, however, manage to acquire a lovely Quarg Horn. The Dwarf was kicked out of town immediately. Obviously The people of this town were prejudiced against Dwarfs. The Warrior Priest did some preaching in the streets, impressing many, and earned himself a loyal companion in the form of a pet dog.
On the upside, the Barbarian bought a shield and throwing axe, improving both his offensive and defensive capabilities. He also bought a mule and cart for the party to use on their future travels, having learned the hard way how much can go wrong just trying to get back to civilization. After this, the party set out on their next adventure.