Slow Horses: What Are the Gray Books? Are They Real?

With season three of Apple TV+’s spy thriller show, Slow Horses,’ the detectives at Slough House, MI5’s dumping ground for trouble agents, find themselves in a new dangerous mess. After Catherine Standish, the department’s office administrator, gets abducted randomly, Cartwright has to undertake an impossible ransom deal and infiltrate the Park. Little do the horses know the kidnapping is a ploy that will pave the way for even bigger trouble that threatens to shake up the country’s entire spy network.

In the season’s third episode, titled ‘Negotiating With Tigers,’ Lamb and his agents discover that Catherine’s abduction and the ensuing ransom demand is a secret internal security test conducted by the higher-ups. However, through some sleuthing of their own, the horses also learn that the assigned Tiger Team has gone rogue and actually abducted the woman with plans to trade her for the Gray Books. Consequently, the question arises: what are the Gray Books, and do they have a basis in reality outside of ‘Slow Horses‘ and its otherwise fictionalized universe?

Gray Books, A Fictional Archive of Conspiracy Theories

Gray Books is a new plot device introduced in the third season of ‘Slow Horses’ and promises to become the storyline’s central piece. The show has always dealt with conspiracies and inter-agency secrets. As such, it’s only fitting when the third season begins with the story of a pair of MI5 agents who are secretly involved with each other while also betraying the other’s trust through their own contradictory sense of duties.

Alison Dunn, the character whose actions incite this season’s events, wishes to leak a sensitive agency file to the public, bringing their secrets out into the daylight. However, once the agency picks up on her treachery, they assign Sean Donavan, the woman’s secret lover, to investigate her, and the man follows through with his orders. Their story ends with Alison’s death at the hands of a faceless organization, which feeds into Donavan’s grief.

The next time we meet Donavan, he’s working for the MI5 through a private security firm, The Chieftans, as the leader of the Tiger Team hired to test the Park’s security. Nonetheless, when the time comes, he reveals his true intentions. Donavan wants to get his hands on the Gray Books, which holds detailed examinations and records of every conspiracy theory that has emerged in the past hundred years.

While the books disprove most of the absurd conspiracies, there is enough evidence for some cases that the authorities find it best to keep the entire matter under wraps. Within the show, the Gray Books are so secretive most people, even heads of private security firms, aren’t known to be aware of its existence. Yet, Donavan knows about them and wishes for them to come under his possession.

Even though Donavan’s motives are up in the air for now, one can imagine his desire to possess the Gray Books likely has something to do with Alison’s storyline wherein she tried to expose the Agency’s secrets. Only in Donavan’s case he’s aiming for something bigger and wishes to disclose all their most well-kept secrets.

In real life, such a collection of MI5’s examinations of conspiracy theories does not exist in public knowledge. Therefore, it is most likely that the Gray Books are a work of fiction created to explore a new adventure within the ‘Slow Horses’ universe. They also have a basis in the show’s source material, the spy book series ‘Slough House’ by Mick Herron, particularly the third installment, ‘Real Tigers.’ Thus, the author can be credited for their creation.

Herron is known for making up spy language and elements in his stories. Consequently, the chances of Gray Books being based on a real-life MI5 document are slim to none. However, it’s worth noting that conspiracy theories have followed MI5 so closely in the public eye that on the organization’s hundredth anniversary, in 2009, they released an authorized history of MI5.

Therefore, perhaps ‘The Defence of the Realm,’ written by Christopher Andrew, a historian who was allowed access to MI5 files, could have been a possible source of inspiration. Still, even though there’s no tangible evidence to suggest the same, the instance provides insight into the public perception of MI5 and its connection to conspiracy theories. Ultimately, the Gray Books are simply fictionalized tools created to move the plot along and exist without any firm basis in reality.

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