I got this softcover from an online seller. It looks to be a riff on the Phantom of the Opera.

Later: Oh, most definitely "Phantom" - in all its incarnations, from the original book to the screen and stage adaptations. But it's in a delightful mashup with the concept of "Charlie's Angels", with the Phantom running his secret agency from the opera house - and employing a variety of "angels of music" to send out on quests opposing everything from vampires to take-over-the-world villains.

As with Newman's "Anno Dracula" series, this one pulls in references to multiple pop-culture sources, from novels by Trollope to comic strips to movies, and applying to major characters as well as throw-away one-liners; part of the fun is in spotting these, though if you want to enjoy the story proper you should probably just try to ignore them and read straight through, going back later for the references.

The stories themselves are a loosely-linked set of five acts, with varying casts of characters as the senior angels go on to other things and new ones are brought in (for a total of 18, as per the list up front - which should itself convey some of the mashups; naturally Christine Daaé is one, along with Trilby O'Farrell and Irene Adler, and later angels include Kate Reed (a different-universe variant of the one from the "Anno Dracula" books), and a trio of characters whose film fates don't quite match their activities here: Gilberte Lachaille, Elizabeth Eynsford Hill, and Riolama, from "Gigi", "My Fair Lady", and "Green Mansions" respectively.

The cases that the angels tackle include a "marriage club" in which ethereally lovely automata are used as wives for wealthy and influential men as a way of gathering power; fake vampires pretending to be real ones (and, just possibly, a few real ones as well - though this 'verse does not share the "Anno Dracula" one in which the vamps take center stage); the Grand Guignol theatre may be taking their blood and gore a bit too far; and a wealthy American named Charles Foster Kane is seeking to meddle in European politics, and the Phantom would like his angels to... discourage him. [That last one opens with the mission being sent on a cylinder that will self-destruct at the end of the message, a la "Mission Impossible"!] The adventures include disguises, special equipment, layer upon layer of plots and counterplots, and some truly amusing encounters - one of my favorites is a high-stakes card game in which Col. Sebastian Moran and card sharp Bret Maverick take part. (Maverick comes out of it in good shape - he definitely knows when to fold 'em!)

Along the way, time passes, the previous angels go through changes of their own, some return to the fold, and the nature of the business itself begins to shift... [Don't miss the final page, "After the Curtain"; it follows the acknowledgements and some ads, so it's easy to overlook, but it repays attention.]

[There's a TV Tropes page on the novel, with some entertaining tidbits.]

Guidelines for safely visiting and stocking Little Free Libraries during the COVID-19 pandemic, from the LFL site here.

I left this book in the icebox-repurposed-as-LFL; hope someone enjoys it!

[See other recent releases in MA here.]

*** Released for the 2020 You're Such an Animal challenge. ***