Ancrum got her start writing on
Tumblr in 2010s and would write during class. Upon graduating from university, she signed her first book deal with
Macmillan Publishers, through which she published her debut novel
The Wicker King in 2017. She originally wrote the story for a friend "who felt alone in his bi identity". This was followed in 2019 by Ancrum's second novel
The Weight of the Stars, a lesbian science fiction romance.
The Weight of the Stars was a 2019
Locus magazine pick. Ancrum wrote her first two novels in a "
vignette" format. Published in 2021 via Imprint (
Macmillan), Ancrum wrote a thriller retelling of
J. M. Barrie's
Peter Pan titled
Darling, set in contemporary Chicago. Announced in 2022,
HarperTeen acquired the rights to publish Ancrum's fourth novel
Icarus, a reimagining of the titular Greek myth as a modern queer coming-of-age story.
Icarus was shortlisted for a
Lambda Literary Award in the Young Adult category and appeared on the
Publishers Weekly list of best books of 2024. ==Personal life==