The Impossible Fortress

An irresistible series about chosen family, high stakes thievery, and what it really means to do good. Perfect for fans of M.G. Leonard and Anthony Horowitz.

It's Gabriel's fourth year at Crookhaven School for Thieves, and it's the most challenging one yet. Along with mastering a new class - Lay of the Land - Upper Delinquents are supposed to start thinking about life after Crookhaven. Their schoolwork is beginning to have real world implications, and this year's Break-In challenge is set in an external location known to be impenetrable - the Impossible Fortress.

But the world outside their school grounds can be a dark and dangerous place. And with the most powerful crew in the underworld, infamously known as the Nameless, out to get Gabriel and his friends, the stakes have never been higher.

The crew need to put everything they've learned so far to the test outside of Crookhaven's gates. But there may be something lurking within those gates that the crew should be wary of too...

The fourth book in the 'criminally good' Crookhaven series, the secret school where students are taught to do wrong, so that one day, they can put the world to rights.

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Release date: January 30, 2025

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J. J. Arcanjo

J. J. Arcanjo is a British-Portuguese author best known for Crookhaven, a children's adventure series built around an irresistible contradiction: a secret school where young thieves learn to break the rules so they can eventually put the world to rights. He fills that premise with elaborate heists, hidden passages, criminal skills, mysteries, and friendships, but beneath the fun is a persistent question about the difference between doing something illegal and doing something wrong.

Arcanjo grew up between the Algarve in Portugal and Devon in England. Books became especially important when he moved to the UK as a child and learned English through reading, an experience that helped shape his attachment to stories from an early age. He later studied Criminology and Psychology at Aberystwyth University before completing a master's degree in Creative Writing and Publishing at City University in London. He also worked in publishing before establishing himself as a children's author.

His background in criminology found an imaginative home in Crookhaven: The School for Thieves. The novel introduces Gabriel Avery, a gifted young pickpocket who expects trouble when he is finally caught stealing. Instead, he receives an invitation to Crookhaven, where students study subjects such as lock-picking, forgery, deception, and "crim-nastics." The school's philosophy turns the conventional idea of a criminal academy upside down: its pupils are taught how to become exceptional crooks so they can use those abilities against people who deserve to be stopped.

Published in 2023, The School for Thieves was shortlisted for the Waterstones Children's Book Prize and launched a five-book series following Gabriel and his friends through their years at Crookhaven. As their skills develop, the mysteries surrounding Gabriel's family and the criminal organization known as the Nameless deepen, allowing the books to grow from mischievous school adventures into increasingly ambitious heists with consequences beyond the school grounds.

Friendship and chosen family remain as important to the series as breaking into impossible places. Arcanjo's young thieves succeed through different talents and personalities, while the distinction between good people and bad people is rarely as simple as who follows the rules. The result combines the pleasures of a boarding-school story with mystery, crime fiction, puzzles, and high-stakes adventure.

The world of Crookhaven reached an even wider audience when the books were adapted into a BBC television series. For a story that began with a hungry boy picking pockets, it was a fitting expansion: Gabriel's secret school for thieves had escaped beyond the page.

Across his fiction, Arcanjo shows a particular affection for clever outsiders, elaborate schemes, and characters who discover that finding the right people to trust can matter more than following the rules.

Crookhaven

At Crookhaven, breaking the rules is part of the curriculum. Hidden away from the ordinary world, the school takes in young people with unusual criminal talents and teaches them lock-picking, forgery, deception, infiltration, and other skills most schools would rather keep outside their gates. There is one important condition: what they learn must eventually be used for good.

Gabriel Avery seems made for the place. A gifted thirteen-year-old pickpocket, he has learned to steal because necessity leaves him few alternatives. When he is finally caught, however, punishment never comes. Instead, the mysterious Caspian Crook offers him a place at a school unlike anything Gabriel imagined existed.

Life at Crookhaven soon becomes much more than lessons in thievery. Students compete to prove themselves as accomplished crooks, tackle elaborate Break-In challenges, explore places they were never meant to find, and discover secrets hidden within the school's history. For Gabriel, those mysteries become increasingly personal. Questions about his own family draw him and his friends toward the Nameless, a powerful criminal organization whose idea of stealing could not be further from Crookhaven's peculiar moral code.

Across five books, J. J. Arcanjo allows Gabriel and his crew to grow alongside the challenges they face. What begins as the excitement of entering a secret school gradually expands into a larger struggle beyond its walls, where classroom tricks become real-world skills and mistakes carry consequences. The young thieves must decide not only how far they are willing to go, but what separates their own rule-breaking from the criminals they are trying to stop.

That moral contradiction gives Crookhaven much of its charm. This is a world where dishonesty can sometimes serve an honest purpose, stealing can become an act of restitution, and being good does not necessarily mean being obedient. Beneath the heists, puzzles, secret passages, competitions, and ingenious criminal lessons is a warm story about friendship and chosen family, particularly the sense of belonging found by children who have spent much of their lives feeling overlooked.

The result is a playful twist on the classic boarding-school adventure, replacing magic lessons with criminal training and heroic quests with carefully planned heists. Yet the central question remains surprisingly serious: if you are taught how to become an excellent thief, what kind of person will you choose to become once you are good enough to get away with it?

Crookhaven consists of five books. The current recommended reading order for the series is provided below.

★ 6.00 (2)

★ 7.00 (1)

★ 7.00 (2)

★ 7.00 (2)

★ 6.00 (3)