Divided Kingdom is a picaresque novel based in a near-future Britain in which the entire population has been defined and divided into four distinct personality groups (phlegmatic, sanguine, choleric and melancholic) in a bid to rid society of its ills.
The Sanguines lived in the Red Quarter; The Cholerics in the Yellow Quarter; the Melancholics in the Green Quarter and the Phlegmatic in the Blue Quarter. Each country has a different way of running things like the Blue Quarter has canals and the Yellow Quarter is industrious. No one is allowed to go from quarter to quarter; there are walls with barbed wire and armed guards.
The protagonist is Thomas Parry, a government official for the Sanguines. He attends a conference in the Blue Quarter and visits a club called the Bathysphere where he sees his life as it was before the division. This inspires him to go on a journey across all the quarters to find out about his past.
Shortly after, the protagonist is taken to see Mr.Reek, one of the teachers at Thorpe Hall. He is told that he will be moved to a new location where he will be integrated into a new family suited to a person of his type. He is also given his name, Thomas Parry, which is used for the majority of the remaining story.
After a time, Thomas is transported via train to his new home where he meets his new father and sister, Victor and Marie Parry. During the remainder of his childhood, Thomas settles into his new environment easily, adopting the Sanguine attitude and persona.
With his childhood drawing to a close, Thomas goes to attend University witnessing the slow deterioration of his adopted family as life after the rearrangement which took their mother/wife away from them wears them down. Towards the end of his time at university, Thomas is approached by Diana Bilal, an employee of the ministry of health and social security. She informs Thomas that he had been watched for some time and were interested in employing him as a trainee assessment officer. Thomas is initially reluctant to take her up on the offer, knowing that his adopted family would be disappointed as it was the ministry who they blamed for the loss of their mother and wife. Thomas is won over and accepts the job when Diana tells him that his family need not know of his true occupation and that they would be granted immunity from ever being rearranged again.
Shortly after joining the Ministry, Thomas gets his first experience of participating in a rearrangement when a young girl is to be moved from sanguine territory (the red quarter) to choleric (the yellow quarter). During his time as an observer to the rearrangement, he gets his first view of a border gate, a complex of high concrete walls, barbed wire and minefields patrolled by border guards.
After gaining his first view of the 'nuts and bolts' of the job, Thomas is visited by the head of the ministry of relocation Mr. Vishram. Upon being asked if he was available for lunch, Thomas agrees to meet the man the following day when Vishram would reveal Thomas's next job. The next day, Vishram takes Thomas to a small restaurant in the heart of the red light district to discuss an upcoming conference that Thomas would be attending. It is revealed that the conference was to be held in the Blue quarter. Realizing the chance to discover something entirely new and exciting, Thomas duly accepts.
A few days later, Thomas finds himself stepping off of a train and into the Blue quarter, typified by its many canal systems that weave their way through the metropolis. As he walks through the city to get to his hotel, he is stopped by a man who forces a small leaflet into his hand saying you may find this interesting (unfinished)