A father leaves a laptop on a sleeping boy's desk and walks out the door. He does not say goodbye. He does not explain. He leaves behind a cracked screen, a Linux partition, and a future his son did not choose.

Thirteen years later, Zach Reeves is twenty years old, self-taught, and living in a council flat in Croydon with his night-shift nurse mother. When he stumbles upon a classified document hidden on a government server, he uncovers something that should not exist: Project Meridian, a secret programme to monitor and control every financial transaction in Britain, trillions of dollars of the world's money.

He cannot fight this alone. He finds three others: Lily, a data science student carrying the weight of her immigrant parents' dreams. Jane, a care leaver from Manchester who has never had a home but has never stopped running. And Steve, the son of a Hungarian intelligence officer, whose discipline hides a capacity for loyalty that will be tested to its limit.

Together they wage a war against an enemy that has no public name, no public face, and no boundaries it will not cross. They are hacked, hunted, and betrayed by someone they trusted. One of them is taken. The others must decide how far they are willing to go to get her back.

But the deeper they dig, the more they discover that the conspiracy is not what it appears. That the exposure they fought for was part of the plan. That the real threat is something far larger, far darker, and far more personal than any of them imagined. And that the man who started it all may be the one person Zach has spent his whole life trying to forget.