Returning to Watchstation Hestus, the team just finishes debriefing when an alert sounds, indicating that a space hulk has appeared on an intercept course. As the only marines on hand, the team is immediately sent to determine if the hulk represents a danger to the Watchstation, and to neutralize it if needed.

Entering the vessel, the team finds that it has been infested by Orks. Fighting their way into the Ork leaders “Thrownchamba”, the team kills the Big Mek and throws the Ork community into disarray.

Continuing their search, the team enters a part of the hulk that was obviously of xenos origin. Within, they found a centaur-like race emerging from stasis sleep. After attempting to fight their way to the xenos ship’s control center, the team is thwarted by the steadily growing resistance of the aliens. They choose to take the easier solution, returning to the Ork infested area to activate a “trip drive” with coordinates that will put the space hulk in the heart of a nearby star.

As the team heads for the exit, they stumble into an intact Imperial chapel where they recover the long-lost remains of a Crimson Fist sergeant and two dozen apothecary gene seed stasis capsules, ultimately learning the truth of the expeditions into the Lord Vincaine’s Regret.

Returning to Erioch again, the team finds the environment unfriendly, and they are largely ignored for some time. Eventually, they are approached by Inquisitor Gens, who asks them to help locate another of his colleagues, the Inquisitor Malachy, believed to be on Spite.

Since the three Watchcaptains that stand as accusers against him are all absent, Watchcommander Mordigael decides to allow the team to take Galdroon with them, under their supervision.

The team proceeds to Spite, where they discover that the world is slowly spiraling out of control under the iron fist of Lord Commander Ebongrave. Numerous murders and disappearances of his high ranking command staff have occurred over recent months, and a large contingent of Imperial Guard stand accused of mutiny and desertion.

Investigating the murders, the team discovers the presence of a Kindred of Kroot on Spite, apparently tracking down Imperial officers with information about the long-forgotten “Operation Untruth”. They eventually track down the Kroot’s hiding place and exterminate their leader.

During the course of the operation, a revolt in the Four Pillars Sedition camp erupts. The team elects to aid the rebels against Lord Commander Ebongrave, tipping the balance of the fight in their favor. Ebongrave hides in his fortified bunker, and his second in command, Lord General Reila Vann, assumes command of the Salient until Warmaster Tetrarchus can be reached and a decision made as to the fate of Colonel Strain and his deserters.

In order to clear Galdroon of the the charges against him, the team decides to investigate his last mission, which was to the planet Phonos. After a tense mission briefing delivered by three Watchcaptains (Scarion, Durg, and Nhemas), the team is given a special crystal rod that would give them access to the facility.

Before departing, members of the team are approached by various individuals asking them to help with certain side missions. One of them was the Inquisitor Toalis Veer, warning the team against approaching the Phonos facility, which he believed was related to ruins he found on Nunc. The team decides to go to Nunc to investigate.

The team finds that Nunc has been claimed by the Explorator flotilla of Explorator-Magos Halvor. The team is forced to negotiate for permission to go down to the surface.

On the surface, the team is able to locate Veer’s ruins, which is revealed to be the long-buried tomb of a race of mechanical beings. After fighting off some of the tomb guardians, the team returns to the Silent Vigil to bombard the site.

Finally, the team arrives on Phonos and locates the hidden facility. Outside the facility, they encounter the Ultramarine Aviel Didos, another member of Galrdoon’s old team. Didos had sworn to prevent anyone from entering the facility, but once beaten fairly and honorable, felt that he had no choice but to allow the team passage. He also gave them an entry crystal identical to the one they received at Erioch.

Entering the facility, the team finds a strange hodge-podge of xenos, pre-Imperial human (a group calling themselves the "Co-Dominion), and more recent Adeptus Mechanicus habitation. They also come under psychic attack from something in the facility, and shockingly discover a phalanx of the infamous “Men of Iron”, apparently awaiting the command to activate.

Eventually, the team discovers a device at the heart of the facility that apparently has the ability to observe distant places and times.

Determining that the site is extremely dangerous, the team exits the facility and returns to Erioch.

Returning to Erioch, the team learns that Galdroon is a deserter, who is being charged for his cowardice. They also learn that another chamber of the Omega Vault has opened, revealing part of a Warp Route chart showing a stable passageway between Arkhas and Atonement. The team is sent to explore the conduit, then recover the Magos Vyakai before returning to Erioch.

At Arkhas, the team must take control of an Imperial voidship that is currently in mutiny, once again using the help of Commissar Falco. They recruit the navigator of this ship to plot their course through the Warp Conduit. Along the way, the discover a previously unknown system that is inhabited by a race of xenos with access to extremely advanced technology. Despite the loss of their Dark Hunter, the team is able to make their escape from the system and finish the journey to Atonement.

On Atonement, they meet Magos Erlan Klute, who convinces them to undertake an operation to destroy a cluster of spore chimneys that would set back the tyrannid invasion of that world, while testing some special gear he has developed to use against the xenos. They succeed in destroying the clutch through the use of a modified cyclonic torpedo. When they return to the base, however, they learn that it was attacked by the Harbinger, apparently using some kind of hybrid Tau/Eldar device to control a group of Genestealers. The purpose of his raid was to steal the rest of the cyclonic torpedo cache kept at Atonement.

During the mission to Eleusis, the team discovers that an unidentified Inquisitor has been destroying evidence. Their investigation suggests that they could learn much more from another Inquisitor, Tellemain, located on Alphos. But, when they arrive at that world, they learn from her Interrogator, Darius, that she has gone missing, just before Darius is assassinated.

Further search reveals that Tellemain was apparently taken by Black Templar marines to the oceanside community of Imperiopolis. The team proceeds to the port, learning that a group known as the Brotherhood of the Perfected Truth has been operating in the area from a hidden base. Determining that they were somehow involved in Tellemain’s kidnapping, they locate and assault the base. Inside, they find Tellemain, held prisoner by the same Emperor’s Children marine captain they fought on Cressid. They defeat the Alpha Legion marines that he was using to kidnap her before he again escapes through a Warp Portal opened by a Chaos Marine Sorcerer with him.

To learn more about Druj, the team travels to the Shrine World of Eleusis to speak to the Deathwatch Kill-Marine Septimus. When they arrive, the various leaders of the Ecclesiarchy here immediately try to draw them into their internal struggles, which the team tries very hard to resist. During their time on Eleusis, the team learns of a series of brutal murders, apparently targeting knowledgable members of the Adepta Sororitas. They ultimately decide to use Canoness Galatia of the Whispering Cloister as bait for what turns out to be a Tyranid Lictor, which they kill thanks to the help of a squad of Flesh Tearers on world to train the local Frateris Militia.

Septimus provides the team with all of his information about Druj, who appears to have vanished some time ago.

Based on information from the Eldar prisoner, the team is dispatched to locate the Eldar Maiden World of Engurru, believed to be the headquarters of the Redemption group. To reach the world, they must travel onboard the Errant Sun through the Slinnar Drift, but no navigator with experience in that becalmed region is available. Instead, the team must hire an independent known as “Slinnar Cy”, located on the world of Sedu. The team again travels aboard the Errant Sun.

Infiltrating the renegade spaceport on Sedu, the team is identified by anti-Imperial elements, but is shown an escape route by a group of Consecrators marines, led by Brother Naaman. They explain that they came to Sedu to extract justice from a local crime lord by the name of Styphus, whom they hold responsible for the destruction of their vessel. The team agrees to help them.

During the operation, the team learns that Styphus is in league with the same mysterious stranger in the bio power armor. They also learn that Styphus was transferring samples of the Genestealer genus to the stranger. The team attempts to stop the transfer, but the stranger manages to escape with one of the xenos.

Completing their favor for the Consecrators, the team locates Slinnar Cy and he agrees to lead them through the Slinnar Drift in exchange for a “future favor” from the Ultramarine, Scaeva. He begins plotting an erratic course with many changes and corrections and doubling back through the becalmed region.

Finally, the Errant Sun arrives at Engurru, and is immediately engaged by voidships crewed by Dark Eldar raiders. After fighting off the raiders, the team lands on the surface, choosing to search the wreckage of a long-lost Imperial void ship for repair materials needed by the Errant Sun. They find that the vessel was once operated by the Frateris Templar, and appears to have been downed by a Deatwatch team led by a Black Consuls dreadnought, which they recover.

The team then goes to assist the Redemption Dire Avengers against the Dark Eldar raiders, meeting once again the lone Harlequin from Oertha and earning the right to speak with Asha in the Webway fortress of Esagila. They give him the broken spear as a gift, and in return he gives them a broken Force Sword that once belonged to a Librarian of the Emperor’s Children named Lucien, who remained loyal to the Emperor when the rest of his legion turned to Chaos. He also explains that he knows of the mysterious stranger, whom the Eldar call “the Harbinger”, but that if they really want to learn about him they must find the “Lost Maiden”, whose location is known only by the Eldar renegade known as Druj.

Returning Inquisitor Bellin to Gens, the team finally gets permission to speak with the Eldar prisoner, who provides them with only a few details they did not already know. He does mention a book of lore that the Deathwatch holds in the Catacombs, known as Otham’s Tome. The team gets permission from Watchcaptain Servais to search the Catacombs for the book.

Entering the Catacombs, the team meets the ancient archivist Aurelius, who tells them where to locate the book. But, as they go deeper into the Catacombs, the team is split by a suddenly closing door while investigating voices. Half of the group is then attacked by a brass automaton.

Later, the team comes across a veteran of the Dark Angels who identifies himself as Zahariel, a name that the team later learns is no longer in use by that Chapter. Letting the marine go, they proceed to the chamber where Otham’s Tome is kept. They later grow suspicious of him when they learn that he used a secret exit to leave the Catacombs. But, they cannot find any marines by that name on the rolls, though Watchcommander Mordigael identifies the armor as belonging to Brother Elyas, who serves under a rival of Watchcaptain Servais by the name of Prascus.

Back on board the Tempestuous, the team experiences powerful dreams of the xenos facility they left behind. Two weeks into the journey, the crew is alerted to dangerous fluctuations of the Gellar Field, just before an enormous group of hullghasts erupts from the lower decks, capturing or killing the Chapter serfs and making off with Inquisitor Bellin (who is being held in a chemically-induced coma by Galdroon).

The team tracks the hullghasts back to a make-shift shrine, centered around a sort of throne built from scrap and equipped with sophisticated life support machinery. They were in the process of installing Bellin into the throne device when the team arrives. They kill off the mutants and their blasphemous cardinal and rescue the Inquisitor.

The team then learns that the hullghasts had damaged two of the ship’s Gellar Field generators, which had to be repaired before the ship was exposed to Warpspace.