Li guessed correctly.
Zhang Ze was indeed plotting something shady.
After Zhang Ze saw what was hidden inside the secret door, he started planning.
Planning how to move all these things back to the Thousand Mechanism Pavilion without being noticed by the Hundred Demons Sect.
Behind the secret door was a large cavern, with a medium-sized array at its center.
The array was composed of several independent Black Stones, each engraved with mysterious dark sigils.
Zhang Ze was familiar with those patterns; although he couldn't understand them, he had seen them several times.
Both arrays in Cold City had similar patterns.
It's likely that this Black Stone array is also related to the Stone Pill.
At the center of the array was a large block of ice, the nature of which was unknown.
Zhang Ze and Lin Feng, along with the three elders, were not experts, so they couldn't decipher much of the setup here.
