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.