Wikipedia page about this book: https://en.wikipedia.org/wiki/The_Blue_Star_(novel)

Release date is 2018-04-01

Produced by Al Haines, Stephen Hutcheson & the online
Project Gutenberg team at
http://www.pgdpcanada.net

"The Blue Star" by Fletcher Pratt is a fantasy novel first published in 1952. Set in a parallel world where witchcraft has evolved into a science while technology has stalled at an eighteenth-century level, the story follows Lalette Asterhax, a hereditary witch, and Rodvard Bergelin, a clerk recruited by revolutionaries. When Rodvard seduces Lalette to gain her magical talisman—a mind-reading jewel called a blue star—both become pawns in a larger conspiracy. Forced to flee, they embark on adventures that transform them from shallow conspirators into something greater. (This is an automatically generated summary.)

Original publication data not identified