Book 1:
The first book, Inquisitor, later reprinted with the new title Draco, revolves around Jaq, Grimm, Meh'lindi and Vitali Googol, Jaq's Navigator, landing on the planet Stalinvast, to follow the efforts of a fellow Inquisitor — Harq Obispal — as he roots out a genestealer infestation, in order to assure themselves of Harq's loyalty.In the process, however, they become aware of a strange new Warp-entity; a "Hydra" that seems to have been artificially engineered to link human minds together through the power of the Warp. This brings them to the attention of the Ordo Hydra; a secret cabal who created the Hydra as a weapon to forcibly unify the minds of all humanity, creating an ultimate psionic weapon with which to purge the Warp of Chaos, and then to annihilate all nonhuman races from the galaxy.
Suspicious of this plan, Jaq and his acolytes track the origins of the Hydra to its birthplace; a Slaanesh Daemon World in the Eye of Terror. Convinced now that the Hydra could be a danger to the Imperium, Jaq's band then dares to infiltrate the Imperial Palace on Terra itself, where he briefly communes with the God-Emperor before being forced to flee the planet. Before going into hiding, he leaves an account of his findings to be delivered to the Inquisition, in hopes of bringing them to bear against the Ordo Hydra.
Book 2:
The second book, Harlequin, takes place one hundred years after the end of the first. Awakening from hidden stasis capsules, Jaq, Meh'lindi and Vitali are uncertain of what has happened to the galaxy whilst they hid from the Ordo Hydra. Attempts to find their way lead them to Luxus, a world being invaded by Chaos worshippers loyal to Slaanesh; here, Vitali dies, having been corrupted by 100 years in stasis meditating on the daemonette he saw in the previous book, but they are also reunited with Grimm. The Squat leads them to another Navigator he had rescued earlier, a man named Azul Petrov. With his help, the new quartet deceive the planet's governor, taking his Astropath for themselves before murdering him for being told forbidden knowledge about Chaos and abandoning the planet to be overrun by Chaos forces, such is their desperation to find out the fate of the Ordo Hydra.Learning that Eldar have been seen gathering around the ruins of Stalinvast, the planet that was subjected to Exterminatus in the previous book, the quintet set upon a plan; to find the disgraced master assassin who altered Meh'lindi to have her Genestealer Hybrid alternate form, and make him undo the surgery, so they can then use the Meh'lindi in Eldar form to infiltrate the event, which Jaq believes might be connected to the Ordo Hydra. Before that, though, they interrogate Grimm, whose presence on Luxus Jaq found suspicious. The terrified Squat reveals that during their century apart, he became an agent for the Illuminati — a secret society of formerly possessed humans seeking to help humanity by guiding the maturation and growth of a benevolent new deity. The Illuminati want Jaq to succeed, because a rogue faction of theirs is behind the Ordo Hydra, and they fear that if the Ordo Hydra's ploy succeeds, it will instead create a new and terrible Chaos God, ripping open reality and making the entire galaxy into a nightmarish space hell, just like the Eye of Terror. He also reveals the existence of the Sensei; the Emperor's immortal sons, psionic blanks whom the Illuminati believe will be essential in kindling their new deity, the cast-off goodness and hope of the God-Emperor, into its full glory.
Jaq's mind is filled with doubt and suspicion — especially once Grimm reveals that the Illuminati wish to make Jaq one of their ranks. Still, he cannot resist the need to battle the Ordo Hydra. He seeks out Meh'lindi's former master, and she is surgically restored to her former glory. Now prepared, they hasten to the planet Stalinvast, where amidst the clamor of a mighty battle between Imperial and Eldar forces, they cross paths with Captain Lexandro D'Arquebus, an Imperial Fists Space Marine whom was the protagonist of Ian Watson's earlier novel Space Marine. Forging an alliance of purpose, they chase the Illuminati agent Zephro Carnelian into the Webway itself, and end up on Craftworld Ulthwe. Here, they learn of the Eldar myth of Rhana Dandra, the apocalyptic final battle against Chaos, and of the mystical node in the Webway where time flows backwards.
This makes Jaq all the more sceptical of the Illuminati's mission, and he rejects Zephro's invitation to join them. The Eldar then attack Jaq's band, and they are driven into the Warpway, where the arrival of a small squad of Space Marines allows them to make a fighting retreat. Here, Naviator Azul has a vision; a map that will lead them through the Webway to the famous Black Library of the Eldar. Captain D'Arquebus carves the map into Azul's gemstone-like third eye, so that it can never be lost, and the group sets out to find the Black Library. Jaq is confronted by a vision of himself, older and clad in Terminator armor, that begs him to turn back and abandon his mission; he simply dispels it with his Force Rod, believing it to be some manner of daemonic or Eldar trick.
Shortly afterwards, they are attacked by Jain Zar, Phoenix Lord of the Howling Banshees, who kills all of the Space Marines except Lexandro — and then kills Meh'lindi. His faith long having been frayed to the breaking point, the death of the woman he loves causes Jaq to snap; he vows to find the place in the Webway where time runs backwards and bring his lover back to life.
The surviving quartet rob the Black Library, stealing the Book of Rhana Dandra, but are forced to kill Azul and cut out his third eye when proximity to the tome drives him mad. Determined to undo that which has happened, they flee the Webway onto some remote world.
Book 3:
In the final novel, Chaos Child, Jaq, Grimm and Lexandro emerge from the Webway on the planet Karesh — ironically, the same world that had once been infested by genestealers, and whose cult the now-dead Meh'lindi had been surgically modified in order to infiltrate and destroy by assassinating its Patriarch. Lost and broken after all they have undergone, they set out for the capital city, trying to devise a plan on what to do. They know they want to use the knowledge in the Book of Rhana Dandra, but they can't do that without some way to translate its alien language into their own.After assorted misadventures in the piously mad capital city, a female thief breaks into their residence in order to steal what she believes is a valuable gemstone — actually the Navigator's Warp Eye that they took from their dead comrade, Azul Petrov. The woman, Rakel binth-Kazintzkis, is almost the spitting image of the dead Callidus Assassin, Meh'lindi, whom Jaq was in love with — and she is a native of one of the worlds from which the basic form of Polymorphine, the shapeshifting drug used by Meh'lindi's temple, is harvested.
Overcome with desire and mad insight, Jaq uses a leftover vial of Polymorphine and an image of Meh'lindi to force Rakel to assume the dead woman's visage in perfect detail. He believes he can literally turn Rakel into Meh'lindi, with the aid of the book. His companions are skeptical, but hope that this can help draw the rogue Inquisitor back from the precipice of madness.
As part of their plans, Rakel is sent to steal a holy relic made of a gold-wrapped Space Marine's thighbone from a local temple — which goes disastrously wrong when she accidentally kills a witness with Meh'lindi's finger-mounted flamethrower instead of the poisoned dart-thrower that she had meant to use, setting the temple on fire. Accepting the carnage as necessary "for the greater good", they ultimately inveigle their way into the meeting of a local pleasure cult, where Jaq hopes to acquire a data-disk that can be used to infiltrate the local Courthouse, the one place on Karesh where an Eldar translation tool may be found. Things turn disastrous when the cult turns out to have a psychic mutant named Lamia as its star attraction; her broadcasting of erotic stimulation clouds Jaq's already befuddled mind, and he nearly completes a Slaanesh daemon summoning rite — and gets close enough that the unmaterialized daemons provoke the attendants to acts of carnal brutality, triggering a riot as they telekinetically claw at the attendees or telepathically push them to inflict violence on each other.
Still, the party do get their hands on the data-disk, and flee the confusion once Jaq has dispersed the gathering daemonic influence. Using the data-disk, Rakel is sent to steal the translator tech that Jaq requires, assassinating one of the local Judges in the process. In the process, she learns that Eldar have come to Karesh, and Jaq makes plans to capture one of them in order to force them to help him decipher the Book of Rhana Dandra.
Weeks later, they get their chance, although it requires battling a band of the local law enforcers. Capturing an Eldar Harlequin, Jaq forces him to teach him how to read the Book of Rhana Dandra by threatening to destroy it if he does not.
Though Jaq studies hard, the Daemon Primarch Magnus, who has long coveted the Book of Rhana Dandra, senses its presence in realspace. He sends Chaos Marines of his Thousand Sons legion to retrieve the tome. The band slays the first to come after them, and desperate for protection, Jaq attempts to take the renegade's Terminator armor for himself. He finds his mind psychically broadcast back in time, back to when he first entered the Webway, and he pleads with his other self to stop — only to be forced back to his own time.
Through an epic battle, Jaq psychically links himself to the Book of Rhana Dandra, and forces it to tell him where he might go in the Webway to rescue Meh'lindi's soul and force it into Rakel's body, thus resurrecting his dead lover. It yields the answer to him, and thus emboldened, they beat a fighting retreat as Eldar and Tzeentchian forces battle it out, fleeing to the Webway.
At this point, the world is in utter chaos; the sun has been destabilized and is condensing, with its intensified heat burning the world. Clueless and hopeless, the natives desperately riot, the anarchy giving Jaq's band cover as they plunge deep into the desert and seek the Webway gate. After many harsh trials, including fighting their way past a nest of surviving genestealer cultists and Lex having to sacrifice an eye to find the opening, they finally reach the Webway and plunge inside.
More misadventures ensue, including a visit to a world being harvested by Tyranids and to another world that has attempted to rebel against the Imperium and which is being invaded by Imperial forces. Jaq learns that the rebels are led by Lucifer Princip, a self-proclaimed son of the Emperor who claims to be immortal. Thinking him a possible Sensei, Jaq resolves to capture him after Meh'Lindi is resurrected. Finally, they reach the place of Jaq's dreams. Through a ritual, he calls back Meh'lindi's soul and forces it into Rakel's body.
And it all goes horribly wrong. The reborn Meh'lindi is utterly mad; caught up in her last moments alive, she attacks her former comrades, seeing them only as Phoenix Lords. She destroy's Jaq's arm and then flees into the Webway, lost forever. This utterly destroys Jaq; in a fit of nihilistic pique, he turns to Lex and feigns having become daemon-possessed, spitting blasphemies until Lex shoots him dead. Grimm and Lex speak to each other about what happened, and resolve to trace their path back to the final planet they visited - Genost, a planet currently being purged of heresy by the Imperium. There, they will wait for the victory to be won, or at least for the Space Marines to inevitably arrive to secure it, meanwhile trying to learn as much as they can about Lucifer Princip. Then Lex will be able to rejoin his chapter, but what Grimm will do is left unclear.
And Jaq finds that his spirit, having died in the Webway, is able to persist beyond death. He is now able to travel the Webway as he wills, and access the collective wisdom of the Eldar dead, learning and understanding more of the nature of reality than any human alive will ever know... but he is also completely powerless to interfere with the physical world, or to leave the Webway. All he can do is watch as his former friends depart, leaving him alone forever.
