Some time ago, noted science-fiction author Erik Clevedon became acquainted with a young prodigy named Percival, and came to believe that the young man was the first of a new breed of humanity: homo peculiar. Clevedon has always been of the opinion that humanity must strive to improve itself through eugenics and selective breeding, and Percival also came to believe that evolution would inevitably result in the extinction of homo sapiens so that a new and improved breed of humanity might rise up in its place. Percival soon came to be feared for his differences, and fled with others of his kind to set up a safe Retreat away from the hostile world of homo sapiens. Clevedon subsequently wrote up his story, disguising the particulars -- for example, Percival is not the young man’s real name -- and submitted it for publication as a sci-fi novel called The Peculiar.

Some years later, in 1950, Percival stops back in to see Clevedon, whom he regards with some affection, like a human might regard a pet. Percival has returned to London to investigate a loss of contact with other Retreats throughout the world; if this is the result of a concerted attack, Percival believes that it may be necessary for the Peculiar to advance their plans for a final solution to the problem of homo sapiens. Before the worried Clevedon can press Percival for details, however, Percival realises that he’s being watched and tackles a large black man standing just outside the window. As Percival and the man struggle, Percival glances back at Clevedon, sees something very odd -- and vanishes into thin air, along with the man he’s fighting.

The next day, Clevedon is visited by an American philanthropist named St John Spears, who claims to be interested in contacting the Peculiar; suspicious, Clevedon insists that the novel was nothing but fiction, but the dissatisfied Spears leaves his chauffeur standing watch outside Clevedon’s house. Nevertheless, another of the Peculiar, a girl named Violet, manages to contact Clevedon without being noticed by the “chauffeur.” She is accompanied by Emily Blandish, who recently spotted Violet picking pockets at St Pancras railway station. Violet was using her Peculiar abilities to cloud the minds of her victims, but Emily managed to overcome this effect and follow her through the crowd. Distracted by her attempt to avoid Emily, Violet was set upon and violently subdued by two men who were dressed as police but were wearing strange earpieces. Emily gave a statement and was released, but, suspecting that the policemen were not what they seemed, she asked her friend Honoré to investigate. The investigation led Honoré to Percival, and hence to Clevedon’s house; however, it now appears that Percival is a time-channeller like Emily, and when he and Honoré came into contact last night, they saw something that caused them to inadvertently leap through Time.

Violet now reveals that she was taken to a deserted townhouse and tortured for information on the Retreat. While her captors were resting, she used her psychic powers to influence a local clergyman to come to her rescue -- and once she was free, she abandoned him to his presumed death at the hands of her captors. Emily and Clevedon are disturbed by her lack of remorse, but nevertheless agree to help her evade Spears’ chauffeur and return to the Retreat -- which is not on a tropical island as Clevedon had claimed in his novel, but is on an isolated farmstead in Wales. The Peculiar lift the Retreat’s psychic force-field to let them in, and they are introduced to a number of Peculiar children, including a time-sensitive named Freia who claims to see a second life hidden inside Clevedon’s time-stream. Another of the Peculiar’s homo sapiens allies then arrives: Gideon Beech, an arrogant playwright who believes that Life is not just an abstract concept but an entity with a will of Her own. Beech now reveals to the Peculiar that their existence is due to a series of eugenics experiments conducted by various nation-states after World War One; their goal was to create supermen, but much to the horror of their creators, the genetically engineered children who resulted from the various experiments soon saw through the meaningless divisions of countries and nations. Their creators are now attempting to track them down and destroy them, and this, Beech claims, is the start of the species war that will end with the extermination of either homo sapiens or homo peculiar.

Honoré and Percival, meanwhile, have been cast into the distant future, having leapt along the timeline of a strange face they saw hidden behind Clevedon’s public human face. Honoré passes out upon arrival, but Percival quickly acclimatises to his weird alien surroundings and is apparently welcomed by the inhabitants. Honoré eventually recovers and spends some time wandering through the weird landscape before being contacted by Sanfeil, the representative of this world’s inhabitants. Sanfeil confirms that his people are the descendants of humanity, and explains that he has developed the ability to witness past events through others’ eyes and to exert a small amount of control over his subjects. Clevedon is one of those subjects, which is why Percival and Honoré jumped along Sanfeil’s life-stream when they saw him lurking behind Clevedon’s own. Honoré is now reunited with Percival, who has been badly shaken by the revelation that the Peculiar are not the next step of evolution but an anachronistic cul-de-sac created by Sanfeil’s meddling. Sanfeil claims to have encountered other beings attempting to meddle with human history, and in order to secure his people’s birthright, he manipulated the past to bring about experiments such as the British Hampdenshire Program, which gave birth to the Peculiar. Now that the Peculiar are nearing maturity and their life essence is strong, Sanfeil and his kind are influencing select homo sapiens to kill them, in order to ensure that the Peculiar’s life essence dissipates throughout the rest of humanity, giving homo sapiens the evolutionary boost it needs to become Sanfeil’s kind. To Sanfeil, the Peculiar are nothing more than a curiosity, and one that must be killed so his people may live.

The Peculiar have given their guests the run of the Retreat, but their overconfidence proves their downfall. Despite his claims to support the cause of evolution, Beech still considers himself a homo sapiens and does not wish to be made obsolete; he thus sabotages the Retreat’s psychic barrier, unaware in his arrogance that his ability to hide his intentions from the Peculiar is the result of Sanfeil’s influence. St John Spears and his men storm the farmstead, catching the Peculiar off guard and forcing them to wear white-noise headsets that distract them from focussing their psychic willpower. Emily is horrified to learn that the men intend to subject their captives to study and experimentation, probably to the death; not even the pregnant Violet is exempt. However, Spears refuses to listen to her pleas for compassion; he has a personal vendetta against the Peculiar, since most of the men under his command in World War II were killed by the survivors of the German ubersoldaten project. Clevedon and Emily are held under guard in the farmstead’s kitchen, and Clevedon, faced with the brutal reality of species war, finds his own moral beliefs wanting.

At that moment, Percival and Honoré return to the Retreat, having leapt back along Sanfeil’s time-line to reach Clevedon. Honoré surprises and knocks out the guard at the kitchen, and helps Percival to rescue Violet; however, Percival has learned humility after his encounter with Sanfeil, and after he telepathically passes on his experiences to Violet -- the mother of his unborn child -- they agree that their counter-attack must be bloodless. The Peculiar’s adherence to the evolutionary imperative has occasionally resulted in the deaths of innocents such as the man who rescued Violet in London; however, Percival now understands that all life is sacred, and that the Peculiar must transcend evolution, not follow its dictates blindly. Unfortunately, Violet reveals that one of their kind, Jimmie, vanished after the attack -- and after he had primed the Peculiar’s final solution, a terminal capable of transmitting a psychic shockwave across the entire planet. If Spears and his men tamper with the terminal, they will wipe out all homo sapiens.

Percival, now understanding that Freia is a time-sensitive like Honoré, frees her and sends her back in Time with Emily; once Jimmie has primed the terminal, Emily and Freia contact him and take him forward in Time to deactivate it, thus solving the problem without creating a paradox. Meanwhile, Percival and Violet rewire the unconscious guard’s earpiece and send out a signal that disorientates the other human guards, enabling the Peculiar to overcome their captors. Percival then informs Spears that his kind no longer intend to fight homo sapiens for the Earth; instead, they use their newly-discovered powers of time-sensitivity and time-channelling to depart from the Retreat and settle in another, more peaceful era. Before going, they activate a self-destruct mechanism set on a timer, giving everybody -- their enemies included -- 20 minutes to get clear before the farmstead is reduced to a crater.