The Lost Key
A stolen GCHQ drive. A former SAS operator pulled back into the shadows. An MI5 officer trying to contain a breach no one wants made public.
Start with Book 1Out now — a three-book series
James O’Neill — British Spy & Espionage Thrillers
The Key Series · British Espionage & Cyber Thrillers
The Key Series follows ex-special forces operator James O'Neill and senior MI5 officer Sarah Sterling as they deal with the fallout from a stolen GCHQ simulation drive and the rise of The Grey Wind, a model built to detect hostile activity across the UK's power, data, and financial systems.
These grounded British espionage thrillers focus on operators, analysts, and private contractors fighting quiet wars inside networks, ports, and control rooms where a small "glitch" can carry national-level consequences.
If you read SAS and MI5 thrillers grounded in real cyber warfare and British intelligence, this series was written for you.
"Intense, fast, hard to put down. O'Neill grabs you in the first chapter and doesn't let go." Amazon reviewer, United States · ★★★★★
Read on your Kindle, tablet, or phone.
Start The Key Series
Three books. One escalating intelligence threat. The Key Series follows ex-special forces operator James O'Neill and senior MI5 officer Sarah Sterling through stolen data, cyber warfare, hostile state pressure and quiet attacks on Western infrastructure.
These British espionage and cyber thrillers are written for readers who like grounded spy fiction, military experience, intelligence work and threats that feel close to the real world.
New to the series? Use the reading order page to start with Book 1, continue with Book 2, and follow the final book in the correct sequence.
The Grey Wind
A cyber espionage thriller about ports, grids, financial systems, Red Team data and a quiet campaign against Western infrastructure.
Continue with Book 2The Ghost Key
The final book in The Key Series. A hidden threat survives inside the operation that began with Lost Key, and now moves again.
Read Book 3Author
Personnel File · Restricted
Designation
James O'Neill
Service
UK Special Forces
Years Active
20+ Years
Theatre
Europe · Middle East · US
Current Location
Active Operations
EYES
ONLY
ONLY
James O'Neill spent more than twenty years in UK Special Forces and private security consulting, working in environments where the difference between an ally and a threat was rarely obvious.
He writes British espionage thrillers shaped by tradecraft, cyber risk, military experience and the pressure of decisions made far from public view.
The Key Series follows ex-special forces operator James O'Neill and senior MI5 officer Sarah Sterling through intelligence threats that rarely reach the headlines: a classified GCHQ drive moving through the wrong hands, a Red Team exercise mirrored in the real world, and a quiet campaign against Western infrastructure.
The Lost Key, the first novel in the series, begins with a missing GCHQ drive and a former SAS operator whose name keeps appearing in reports where it should not. What follows is a hunt from Belfast to Warsaw and the realisation that the drive is already being used.
The Grey Wind, the second novel, picks up a year later. Someone is applying invisible pressure to Western ports, power grids and financial systems. When the pattern starts to mirror a classified Red Team exercise, the question becomes how far their own side helped build it.
The Ghost Key, the third novel, brings The Key Series to its conclusion. Something buried inside the operation that started with Lost Key has survived, and now it is moving again.
The series draws on direct experience with the environments it depicts, not as background colour, but as the operating logic of how characters think, move and make decisions under pressure.
These books are written for readers who like SAS, MI5, GCHQ and cyber thrillers grounded in British intelligence and real-world pressure.
Books
The quietest operations leave the deepest damage.
When a classified GCHQ drive disappears, there's no explosion. No headline. Just a file called Lost Key moving through the wrong hands — and a former SAS operator who knows that the quietest problems are always the most dangerous.
James O'Neill didn't go looking for this. But his name is showing up in the wrong reports.
An old MI5 contact. A hunt from Belfast to Warsaw. A drive that can quietly unlock the West's most secure infrastructure — and hostile states who are starting to realise what they're holding.
Every step is watched. Every contact is a question. Nothing is real until it happens three times.
"The twists feel earned, not forced. You keep saying just one more chapter and suddenly it's way later than you planned." Amazon reviewer, United States · ★★★★
"Fast-paced without feeling rushed. The realistic feel helps it never feel confusing." Amazon reviewer, United States · ★★★★★
No sirens. No headlines. Just damage.
A year after Lost Key, James O'Neill wants a quiet life. MI5 officer Sarah Sterling wants to close the file. Neither gets what they want.
Someone is running a quiet campaign against Western infrastructure — ports, grids, financial systems — applying pressure without fingerprints, without triggering open conflict. When the attacks start mirroring a classified Red Team exercise, the question stops being who's behind it.
The question is how far their own side helped build it.
"Keeps the stakes high without relying on explosions or spectacle. Small clues unravel big conspiracies." Amazon reviewer, United States · ★★★★★
"If you love Tom Clancy, give this a try. Full of action and fast-paced. Could not put it down." Amazon reviewer, United States · ★★★★★
A James O'Neill Thriller · Out End of June 2026
Some secrets never die. They wait.
James O'Neill and Sarah Sterling are not finished. The Ghost Key brings The Key Series to its conclusion.
Something buried deep inside the operation that started with Lost Key has survived. It has been patient. It has been watching. And now it is moving again.
Some secrets never die. They wait for the right moment. This is it.
eBook only · Kindle and all major platforms · releasing end of June 2026
News & Updates
- Series Guide The Key Series Reading Order — Start with The Lost Key, continue with The Grey Wind, and follow The Ghost Key as the final book in the series.
- New Is the tradecraft in British spy fiction actually real? — Notes from the author on real tradecraft vs fiction.
- Out Now The Lost Key is available on Amazon Kindle, all major eBook platforms, and paperback. If you've read it, a review on Amazon or Goodreads makes a real difference — thank you.
- Out Now The Grey Wind, the second James O'Neill thriller, is also out now on Kindle and all major eBook platforms. Join the Briefing List →
- Follow Along Behind-the-scenes updates and occasional special offers on Instagram: @jamesoneillthrillers
Contact
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Film / TV / audio rights
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