The Butterfly Assassin

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Innocent by day, killer by night: a dark, twisting thriller about a teen assassin’s attempt to live a normal life.
Trained and traumatised by a secret assassin programme for minors, Isabel Ryans wants nothing more than to be a normal civilian. After running away from home, she has a new name, a new life, and a new friend, Emma, and for the first time in Isabel’s life, things are looking up.
But old habits die hard, and it’s not long until she blows her cover, drawing the attention of the guilds – the two rival organisations who control the city of Espera. An unaffiliated killer like Isabel is either a potential asset . . . or a threat to be eliminated.

Will the blood on her hands cost her everything?

From Finn Longman, an exhilarating new voice in YA fiction, comes a blockbuster new series for fans of global phenomena The Girl with the Dragon Tattoo, Killing Eve and The Hunger Games.

Content Warnings

This book contains:

  • on-page depictions of murder, death, and associated violence
  • descriptions of poisoning and associated symptoms, including vomiting
  • hospital scenes and references to past medical abuse/non-consensual surgery
  • flashbacks to and discussion of past child abuse (physical and emotional)
  • brief references to spiders (not described at length)
  • liberal use of swear words

It does not include any sexual content, including sexual violence.

I’m happy to provide more details or warnings to those who need them, so please ask if you have any questions or concerns.

You may also want to check out my introductory post with FAQs, or this post about Isabel’s asexuality and the issue of representation.

Where to buy The Butterfly Assassin:

UK and Ireland:

Chains etc:

*These are affiliate links, so it’ll earn me a small commission if you order through them. You won’t be charged any extra.

Indie bookshops I know and like:

Signed copies may be available from Gay’s The Word, Housmans, and The Little Bookshop, while stock lasts; The Little Bookshop and The Snug Bookshop have signed bookplates available.


Published by Bragelonne, translated by Alison Jacquet-Robert:

Prizes and Praise

‘This dark, enthralling thriller is a compulsive debut’ The Guardian 

‘An immersive, fast-paced thriller’ The Irish Times

‘A heart-in-your-mouth thriller that grips you from the first page until the very last.’ Benjamin Dean, author of The King is Dead
‘A bold, jagged and uncompromising thriller that will keep you guessing all the way to the end.’ Tom Pollock, author of White Rabbit, Red Wolf

‘Sharp and layered, with a bright beating heart. The Butterfly Assassin will lure you deep into a fascinating and dangerous new world.’ Rory Power, author of Wilder Girls

‘An utterly addictive story. I told myself “just one more chapter” well into the night.’ Emily Suvada, author of This Mortal Coil
‘Fierce, thrilling, and impossible to put down. Packed full of amazing friendships, plot twists and a desperate fight to survive’ C. G. Drews, author of The Boy Who Steals Houses