After I arrived at Luk Yu's place, I applied glutinous rice to his father's wound. The rice turned slightly black, indicating the presence of corpse poison in the body. This meant that Baldy was indeed poisoned by the corpse, but perhaps because he was possessed by the dark shadow, he did not turn into a corpse himself.
I had Luk Yu cook some glutinous rice porridge for his uncle to eat, as internal consumption coupled with external application could significantly clear the corpse poison.
Once everything was taken care of, I went back to the west room, collapsed into bed, and fell into a deep sleep. It was so comfortable that I slept for a full day and night. Later, Luk Yu told me that we had stayed in that tomb for a whole week, a fact that astonished me. I had no idea how I had survived; a week with only a piece of biscuit to eat? It seemed there indeed was a mystery to that tomb.
But as to what it was, I had no clue.