From the front cover:
Castle Zadrian is a d20 System adventure booster designed for 3-4 characters levels 4-5. It can be played as a stand-alone adventure or dropped into any ongoing campaign setting.
From the back cover:
When you read the posting for this job, you knew what you were getting yourself into.
"Lady of means requires the assistance of a stalwart group of adventurers willing to undertake a mission of the utmost importance. Discretion is required."
Words like that never mean that the woman in question is looking for someone to weed her garden--unless, of course, it's full of man-eating plants. Those are the kinds of words you only post if you're really in a bind. If it's a matter of life and death. If you're desperate for help and willing to pay for it through the nose.
It just so happens that you've made yourself quite a reputation lending just that kind of aid to people in just that kind of need. And the money hasn't hurt you any either. So when Lady Elena Zadrian tells you that her father--the near-legendary alchemist Sir Timoth Zadrian--has gone missing, well, you're not all that surprised.