The Silver Veil of Carnola (D&D5E: Dungeons and Dragons Compatible Adventure Book)

The new owner of an old abandoned theater has tasked the players with making sure that it is safe so that he can send his workers in to renovate it. There is just one problem though: The theater doesn't have a rat infestation problem. Rather, it seems to be haunted by a very famous singer, as well as many of its former workers and attendants...