Tracey Felstead loved her job as a subpostmaster. After taking up work in Camberwell Green Post Office aged seventeen, Tracey was welcomed with open arms by older workers, who were deep sources of encouragement throughout her early days on the job. Soon, these people would feel like family to her, and she would quickly become part of the workplace social fabric.

The mood began to sour, however, when the money on Tracey’s till appeared to begin dipping. At first it was considered a mistake and authorities gave her the benefit of the doubt. But the apparent hole in her finances deepened, and it seemed she was ‘down’ by £11,500 within a relatively short space of time. Soon, she was taken aside by Post Office authorities who announced that they were launching a formal investigation into her.

During the investigation, Tracey’s self-confidence crumbled. Despite there being no evidence whatsoever against her, the intensity was getting to her. She found herself the victim of a local whispering campaign, and the overwhelming stress saw her attempt to take her own life. After being charged and brought to court, she was called a liar, a thief who preyed on the vulnerable, and a disgrace to her family.

Despite entering a not guilty plea, Tracey was jailed for three months. While inside, she was placed on suicide watch. She found the body of her fellow prisoner who had hung herself in a cell, began suffering harrowing nightmares, and has suffered from mental health issues since her release.

It was only last year—two decades since her incarceration—that Tracey’s name was cleared by the Court of Appeal. Alongside her were thirty-eight other workers who had been the victims of a serious cover-up related to Horizon, a system used by the Post Office for the counting of money.

The truth is that Horizon was a shoddily assembled system, rife with bugs and fundamental structural errors, that could not be relied on to accurately account. This was known at the top, but never properly addressed; the price of this evasion of reality was paid for by scores of working people.

The full story of this injustice has finally been told in The Great Post Office Scandal, a new book by Nick Wallis. Shining light on every imaginable aspect of the situation, Wallis—a former BBC journalist and relentless advocate of the victims—has compiled a landmark history of the situation these workers found themselves in, and their fight for justice.

Through the testimony of IT technicians who had contacted him, Wallis paints a picture of the anarchy that reigned in the construction of Horizon. Having been created through a Tory government PFI scheme to the tune of £1 billion, the hope was that Horizon could reduce fraud and greater rationalise the existing system.

The project was deemed too big to fail. But a former tech worker on the project told Wallis under strict anonymity of how the serious work of coding and planning quickly turned into people ‘firing any old shit’ into the system, with clueless managers hopelessly ‘overseeing’ the work being unable to chart its development. One of the glitches created by this haphazardness was that—to the alarm of many postmasters—huge amounts of money could suddenly go ‘missing’ from the system. No formal structure could assist concerned workers, and each individual worker was insidiously told by the powers that be that they were the only people experiencing problems.

As a result of this inability to communicate issues, workers were terrified, often existing in a state of mental torture for months and years on end. Much-loved pillars of their communities were made bankrupt or homeless after their legal battles. Seema Misra was jailed while pregnant. Noel Thomas offered a huge amount of his annual salary to pay off financial discrepancies because he didn’t want his village’s Post Office to attract negative attention and fall victim to cuts. Martin Griffiths took his own life after being audited for vanished money and being treated with a suspicion so great that when burglars stole money in a raid where he was beaten with a crowbar, he was still ordered to pay a fee for money lost.

The Great Post Office Scandal also casts a light on the behaviour of powerful, increasingly unaccountable forces in institutions like the Post Office. Errors were covered up, justice was designed to be as difficult as possible to find, and workers were made to feel as atomised as possible when describing the problems that were often destroying their private lives and professional reputations.

None of this mattered to senior management. Wallis describes its ‘prosecution frenzy’: by 2010, approximately 287 people were employed to investigate potential employee criminality, and by 2015 over 700 Post Office workers had been ‘uncovered’ as fraudsters. Even more sinister manoeuvres are alluded to: when Noel Thomas requested to see documents seized from him by Post Office investigators upon his suspension, he was told these papers—which detailed his problems with Horizon and also evidenced his cutting a deal with managers to pay his own money into the system to cover losses—had been lost in a fire.

But against this bitter situation, Wallis sensitively recounts the spirit of workers who stood up for themselves. The resilience of these people and their loyal families is clear and inspiring, as they tracked down others who had been in their shoes, refused to accept the degrading tag of criminality, and fought—through networking, protest, parliamentary lobbying, media pushing, and delicate legal work—to draw concessions and a just outcome from the Post Office and the legal system.

In The Great Post Office Scandal, Wallis has produced an authoritative account of one of the most appalling injustices of the past three decades. It is a harrowing portrayal of the manipulation of power by the powerful over the powerless, and how the gross delusions of those at the top can lead to the darkest scenarios for those who do the work.

At the time of writing, the Post Office is facing compensation claims of around £1 billion from victims, who have faced shame, smear, imprisonment, mental illness, and—in one case—even death. No senior figure has faced accountability, which has led the Communication Workers Union (CWU) to call for a criminal investigation, demanding that ‘heads must roll for the humiliation and misery’ inflicted.

But it is also a stark warning about private sector involvement in beloved institutions like the Post Office. The Horizon scandal is an ominous example of unaccountable corporations being given license by governments to waste essentially unlimited amounts of taxpayer’s money on faulty systems that can result in the literal destruction of innocent people’s lives. And a key guarantor to avoid further repeats of injustices like these would be the transformation of the Post Office into a far more transparent, democratic body, in full public ownership, and run in the fundamental interests of its workers and communities who use it.