Written for children, probably in the 9-12-year-old range, I'm here to tell you that it's suitable for EVERYONE. Yay!
This book begins in 1906 London, in the Museum of Legends and Antiquities. Theodosia Throckmorton's father is the head curator, and 11-year-old Theodosia is his unofficial assistant, although he doesn't know it.
She has the peculiar gift of being able to sense magic. She can see spells swimming in the moonlight on ancient Egyptian artifacts. Ancient Egypt, in fact, seems to be her specialty. She can read hieroglyphics like you and I read the ingredients on cereal boxes, and understands them better, no doubt. She devises amulets of protection and calming spells for curses out of (mostly) everyday ingredients. (One does have to develop a reliable source of myrrh, however.)
Largely ignored by her globe-trotting archaeologist mother and absent-minded father, she yearns for their approval but knows they would rein her in -- i.e., send her to boarding school -- should they suspect her paranormal activities. So subterfuge serves her well in trying to help and protect them and the museum.
Theo's mother brings back a bauble known as "The Heart of Egypt" from the Valley of Kings in Egypt. It has serious bad mojo attached to it and the bad guys -- i.e., German spies, who turn out not to be so much German spies as servants of the Serpents of Chaos -- want it. It is up to Theo, her adversarial younger brother, Henry, and a Dickensian pickpocket named Sticky Will to thwart their plans and neutralize the artifact. Theo is unofficially conscripted by "Brotherhood of the Chosen Keepers," a secret organization of grownups who are trying keep chaos at bay.
So much fun. So much magic. And a black cat named Isis thrown in to boot.