Terry Pratchett has a stab at satirising opera in his own version of the story of the Phantom.
I do find it funny that he has a Frank Spence like character (given that he is played by Michael Crawford who has also sung the part of the Phantom of the Opera).

This is technically a Witches story though there is some crossover with the Watch, and a cameo from the Librarian.

All the characters behave as they ought.
I think it's a bit naff that we lean so hard into the fatphobia in this offering, but the plot is a solid whodunnit.