Twelve-year-olds Tinn and Cole, raised as human twins in sleepy Endsborough, risk their lives in the Wild Wood, Oddmire Swamp, and the Deep Dark to learn which is a goblin changeling with an important mission. --

"An autistic changeling trying to navigate her unpredictable magic, Seelie finds it difficult to fit in with the humans around her, unlike her twin sister, until they both get caught up in a heist gone wrong that changes everything"--

Bedeviled by evil fairies that only she can see, thirteen-year-old Tanya is sent to stay with her cold and distant grandmother at Elvesden Manor, where she and the caretaker's son solve a disturbing mystery that leads them to the discovery that Tanya's life is in danger.

Sixteen-year-old Mackie Doyle knows that he replaced a human child when he was just an infant, and when a friend's sister disappears he goes against his family's and town's deliberate denial of the problem to confront the beings that dwell under the town, tampering with human lives.

When Wendy Everly was six years old her mother was convinced she was a monster and tried to kill her, and eleven years later Wendy learns that her mother was right and that she is actually a changeling troll, who, at the age of seventeen, must be returned to her rightful home.

When San Francisco adults forget who they are and mysterious exotic birds flock to the city, twelve-year-old Winston Chu and friends team up to investigate the strange occurrences and face off against Mr. Pang's older magpie-turned-human brother, Mr. Gu.

Duty-bound to marry her friend Tove in order to give the Trylle people their strongest king and queen in history, Wendy, a changeling troll princess, is torn between two other suitors, Finn and Loki.

"A young troll named Hawthorn is stolen from Fairyland by the Golden Wind, and becomes a changeling in our world, a place no less bizarre than Fairyland in his eyes"--

Pikey Thomas doesn't know how or why he can see the changeling girl. But there she is. Not in the cold, muddy London neighborhood where Pikey lives. Instead, she's walking through the trees and snow of the enchanted Old Country or, later, racing through an opulent hall. She's pale and small, and she has branches growing out of her head. Her name is Henrietta Kettle. Pikey's vision, it turns out, is worth something. Worth something to Hettie's brother...

Now living at Elvesden Manor under her real name of Rowan, Red attempts to put her past behind her, while fairy messengers try to convince her to participate once more in the changeling trade and she is haunted by dreams of an old enemy who is determined to exact his revenge.