Gemma Doyle is a girl in her mid-teens who is rather less than thrilled with her lot with life with her mother in India. She dreams of going back to her native England where her father resides, and taking up the society life to which she believes she's entitled.
Gemma should be careful what she wishes for, because when her wish comes true, it’s at the cost of the tragic death of her mother. One day, out in the hot and dusty market place in Mumbai, Gemma's mother is approached by a man accompanied by a boy who is conveniently Gemma's age. The man relates a cryptic message to Gemma's mother, and her mum then demands that Gemma return home immediately. Gemma becomes so frustrated with her mother's secrecy that she runs away, and gets herself lost. She's visited by a horrible vision of her mother committing suicide, and when she finally makes her way to where her mother is, she discovers that her vision was true: her mother is dead, and subsequently Gemma is being hastily packed off to England, to be sequestered at the elite Spence Academy.
Gemma starts out by being the lonely newbie because of her derided Indian background, but when she discovers the snottiest girl in school, Felicity, in a compromising situation, Gemma finds herself elevated to the top notch of clique-dom. Finally, she's where she wanted to be. She begins to form a close relationship with Felicity and her two friends, Pippa and Ann. Gemma also learns that Kartik, the boy she saw with the man in Mumbai, is now in England! He warns her that she is in danger, and must close herself off to what happened to her mother if she wishes to remain safe.
Gemma increasingly has visions and one of these leads her to a cave in the school grounds, where she finds a 25-year-old diary written by Mary Dowd, a girl of Gemma's age, who also was a student at Spence. Gemma identifies with Mary because May also had visions which she shared with her friend Sarah Rees-Toome.
Gemma reads the diary and discovers that Mary was associated with a society known as the Order, initiates of which were able to open a portal to other realms. They could use this power to ease the passage of souls, and the power gave them prophetic insight and the power to create illusions. The four new friends create their own "Order", meeting in the cave.
As they read more of the diary and investigate the history of Spence, they discover that the two girls from a quarter century ago died in a fire at Spence along with the principal of the school.
Finally Gemma & Co travel to the realms which are weird, beautiful and wonderful. They do not travel there bodily but spiritually, leaving their bodies behind in the real world. Gemma is able to meet with her mother there, but predictably her mother is unnecessarily mysterious. She does, however, warn Gemma not to take magic from the realms into the everyday world because it would let them fall foul of Circe, who seeks this power and wishes to take over the realms. The magic of the realms allows them to have a wish granted. Ann, who is plain, requests beauty. Felicity, who feels abused, asks for power. Gemma wants insights into her self, and finally, Pippa seeks true love.
The girls begin a routine of secret night-time meetings in the cave when they visit the realms. Gemma discovers that her mother was Mary Dowd, who obviously she did not die in the fire but escaped and changed her name. She also learns that Sarah is Circe.
Gemma is the only one who can control the portal, and during one visit, Pippa is separated from them and is left behind as the others flee an evil power seeking them in the realms. Back in the real world, Pippa is now having a seizure. Gemma returns to the realms to retrieve Pippa, but Pippa has met her true Love there and refuses to return to real life and the arranged marriage which awaits her there. When Gemma returns to her own world, Pippa is dead.
I've also listened to the audio book version of this, narrated by Jo Wyatt, and I recommend that version, too. She does a thoroughly amazing job of narration and voices. I've had good success with Libba Bray, and although this is a series (a trilogy specifically) which I usually detest, this one turned out to be eminently engaging. I recommend it.