The Door by the Staircase by Katherine Marsh

Mary is an orphan who is adopted by a kindly old lady, Madam Z.  For the first time since her family's death Mary has someone who seems to care about her.  Her new guardian lives in a village full of fake practitioners of magic, but as time goes by Mary begins to wonder if some of the magic might be real.  She also wonders if Madam Z is as harmless as she seems.  Luckily Mary has a new friend in town, the son of a two-bit magician, and together they make plans to find out what is really going on.

I enjoy stories that draw on traditional folktales, especially cultures with which I am less familiar. This one is full of references to Slavic folktales, including, of course, Baba Yaga, but also Koschei, the Firebird, a Domovoi and others. Mary is a likable character, intelligent and brave, who is very wary of her new life and caregiver.  Madam Z is also a complicated character, and I honestly didn't know, half way through the book, where the author was going to take their relationship.  This is a great middle grade fantasy,  exciting, interesting, and just a little scary. 273 p.