From the front cover:
Tomb of the Overseers is a d20 System adventure booster designed for 5-6 characters levels 3-5. It can be played as a stand-alone adventure or dropped into any ongoing campaign setting.
From the back cover:
Nearly 100 years ago, Lord Eriador wrested the lands from the hands of evil and began a reign of unsurpassed courage, wisdom, and might that lasted over three centuries. One day this great man of valor was called onward to continue his battle for freedom and goodness on a higher plane of existence. Leaving the responsibilities of rulership to his faithful overseer, he donned his magical shield, helm, and sword and traveled to the Holy Mountain of Anduin to meet his destiny.
Eriador left the overseer with his solemn promise: if there ever arose a time of great need, he would answer a summons from the Mountain of Anduin to come back to vanquish any evil that dared to oppress his people.
It is now the reign of the third overseer. For years now, an evil mage has been plaguing the land by sending for hordes of evil humanoid minions to oppress the people. The overseer has been forced to pay tribute to the mage to protect his people. Life has become nearly unbearable for his subjects....