The Mesmerist by Ronald Smith

 Jessamine Grace's father has died and she and her mother survive by offering fake Spiritualist encounters for gullible Victorians. Then one day, the sham becomes real and Jessie is thrust into another side of England that she never knew existed.  Little does she know when her mother takes her to the enigmatic Lord Bathesar, that he will hold the key to a future of fighting evil on a scale she had never expected.

This is an odd story.  Smith mixes the Victorian obsession with spiritualism with the terror of the bubonic plague and throws in some necromancy for good measure.  The book kind of has the "Lockwood and Co" vibe, but the world building and character development isn't quite as good.  I think Jessie goes from prissy, timid, Victorian girl to totally awesome demon fighter to quickly and easily. Still, I enjoyed it and would recommend it to fifth or sixth graders who were looking for something a little spooky.  I think it was written as the first in a series, but I cannot find that any others were ever done. (2017, 272 p.)