Sara Bergmark Elfgren (a.k.a. Sara B. Elfgren) is an award-winning Swedish writer, screenwriter and playwright. She made her debut with the YA novel The Circle (2011), which she co-wrote with Mats Strandberg. The Circle was the first part in the Engelsfors trilogy, and it has been translated into twenty-five languages. Since her debut, Elfgren has written critically acclaimed novels, children's books, graphic novels, audio dramas, plays, screenplays and TV scripts. She was born in Stockholm and still lives there. She has a degree in Film Studies. She enjoys reading, watching old movies, listening to music, playing video games and going for long walks. She is currently working on an opera libretto, a new novel and a children's book.

Jenny Jägerfeld made her literary debut in 2006 with a hole in my head. Her second novel, Me on the Floor, Bleeding, was in 2010 rewarded with The August Prize for best youth novel in Sweden. It’s her first novel translated to English. Originally a child psychologist, she now runs her own psychologist practice in Stockholm. She also works for the Swedish national radio, in a radio show about psychological matters.

Katarina Kuick är en svensk barnboksförfattare och översättare. Hon är även ledamot i Svenska Barnboksakademin där hon innehar stol nummer 13. Kuick debuterade med bilderboken Inte mycket att hänga i julgran 1986, och har skrivit bilderböcker, faktaböcker, lättlästa böcker och ungdomsromaner. Hon har översatt ett trettiotal böcker och har jobbat speciellt tätt tillsammans med den engelska författaren Aidan Chambers.