Cari Thomas has always loved magic, inspired by her upbringing among the woods and myths of Wales's Wye Valley. She studied English and Creative Writing at Warwick University and Magazine Journalism at The Cardiff School of Journalism. Her first job was at teen Sugar magazine, where she ran the book club and quickly realised she wanted to be the one writing the books instead.

She went on to work at a creative agency, spending her spare time researching magic and accumulating an unusual collection of occult books. She wrote her first novel, Threadneedle, while living in London, wandering the city and weaving it with all the magic she wished it contained. She now lives in Bristol with her husband and son, who bears the appropriately Celtic name of Taliesin.