The High Library of Magic would usually send more important people to look at this sort of thing, but they live nearby and people higher up in the pecking order were busy. So they packed things for a day trip and went investigate the unearthed ruins. The initial readings didn't show any sign of anything actively magical.
The initial readings didn't go deep enough, and they discover a chamber that hadn't seen light for millennia.
Then things start spinning. That's never a good sign in an ancient ruin and thing though Felix is fast, but he needs to plant his limbs somewhere solid.