By the time Chromie returned to his temporary base, it was already completely dark.
His gaze was instantly drawn by something on the table: a box made of an unknown material, which was accompanied by a yellow-stained book underneath.
The book explained very clearly what the box on top of it contained.
After killing the three Soundless cultists, Negary had also extracted their remnant souls.
The thing inside this box was the remnant soul of one of the Soundless cultists, and if Chromie was determined enough, he would be able to use this Spirit Vision ability to collect the information he wanted from the soul.