An Assassin lurks on board the Vengeful Spirit. His target? Warmaster Horus himself.
Eristede Kell, an Imperial assassin of Clade Vindicare, confronts a man in the bowels of the Sons of Horus' flagship Vengeful Spirit. Reflecting on a series of events, Kell recalls infiltrating the ship and setting up a hide across an internal canyon from a platform where he knows his target, Horus, will stand. Accidentally discovered by a crew serf, Letae, the terrified man thinks Kell has been sent to kill him because he remains loyal to the Emperor in his heart and only pays lip-service to worshiping Horus and his daemonic allies. Interested by Letae's loyalty, Kell strikes up an alliance with him and Letae begins secretly bringing supplies to him while he prepares for his kill. However, Kell was injured when his life-pod punctured the Vengeful Spirit's lower decks and he was subsequently attacked by venomous snakes dwelling in the ship's underbelly, leaving him mentally unstable and missing large portions of his memory. Consequently he remembers only the broad sweeps of his mission to Dagonet with a team of other assassins in which they killed Luc Sedirae instead of Horus and all of the team bar Kell died stopping a daemonic assassin sent after the Emperor, a mission which ended in Kell aborting his suicide run at the Vengeful Spirit's bridge and entering the ship via life-pod at the last moment. Back in the present but unaware that he has been aboard the ship for years, Kell succumbs to the whispers that have been playing in his mind since he survived the snake attack and snaps, demanding that the man, Letae, tell him where the whisperer, Samus, is. He accidentally kills Letae while the serf is protesting that Kell is out of touch with reality, and heeding the whispers' advice carves the word Lupercal into Letae's corpse and dumps it on a supply cart to draw Horus to him. When Horus arrives on the platform Kell is terrified out of making the shot but fires his sniper rifle out of reflex, yet Horus catches the bullet in mid-air. Confronting the assassin, Horus plays on Kell's resentment towards Malcador for sending him on such a suicidal mission and carves a Chaos symbol onto his palm, arming him with a new gun and turning him into a servant of Chaos.