On board the Ultramarines vessel Spear of Macragge, in transit through the warp, Primaris Space Marine Apothecary Polixis has a confession to make. In the Chapel of the Dioskuri, he kneels before Chaplain Castor, black-clad and implacable, and tells a tale that could damn him to death, or perhaps save his soul: the story of how he killed his battle-brother, Artimaeus Tulio of the Fulminata.

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It's a story showing the way the Primaris Space Marines interact and how they view the common folk of humanity that they defend.