Synopsis
In the present Gamora in her starship Lachesis relates her origin to someone. Who that is will become clear later in the series. For now we are only told that she wants to tell him now rather than later when he'll be dangerous. She doesn't expect him to understand her tale now so she'll record it and he'll be able to make more sense of it later on.
She tells him of the massive starship where she grew up, Alpha Prototype 0: Base Ship Sanctuary or Zero Sanctuary for short. The warlord Thanos had been building it for years while he gathered his galactic army, and it has grown rather haphazardly. At the beginning of the story she herself is not yet there.
She tells instead of part of its crew, the elite Butcher Squadron consisting of Ballista Grim (an assassin), Ebony Maw (a neophyte), Ferox (a fool), Infesti Macera (a living hive) and Proxima Midnight (a joyful killer). (I must say the squad doesn't sound very elite.) Things have been boring for the last 2 weeks. Ferox leaves their card game to relieve himself and Proxima warns him not to become 1 of those crew members who somehow disappears. He gets lost in the confusing corridors which seem to change from day to day, and then gets dragged off by the captain who slices him open as an offering to Death who we see behind him, but no-one else but him can.
Next day Thanos calls the troops to action. Proxima Midnight remembers hearing a scream last night. Ebony Maw comments to the remains of Butcher Squad that Ferox hasn't been seen, and he remembers the 5 previous consecutive occasions when the boss led a raid immediately after a crewman vanished. Then the Mad Titan takes them down to a planet to kill all the pacifist Dorcaernir which they do efficiently.
Back on Sanctuary newbie Ebony Maw expands on his theory. Thanos' bloodlust wanes. Then a crewman goes missing and the boss orders genocide on the nearest available planet. He agrees with Ballista Grim that it's not very satisfying killing people who only run away. Thanos overhears and accuses them of questioning his orders. Sly Ebony suggests that it's better to have their informed consent rather than blind obedience, but Thanos says blind obedience is all he needs. Ballista and Proxima ask why the pacifists had to die, and he replies that they could still be spies for his enemies. But he assures them of more challenging prey next time.
He returns to his quarters and asks his computer what his greatest current threat is. It reminds him of Magus, leader of the Universal Church Of Truth who roam the universe converting alien races or destroying ones that refuse. Thanos comments that the Dorcaernir were targets of the Church (but presumably Thanos destroyed them before the Church could get there), and he asks who's next. The AI tells him it's the planet Lazareen. Thanos already razed it but the population have regenerated from larvae. The Titan doesn't relish ordering his troops to stomp eggs before they hatch, and wants to attack Magus directly. But the AI reminds him that Sanctuary needs lots of repairs, and suggests that they would lose an open war. Thanos decides to continue taunting his opponent.
Butcher Squad are playing cards again with another guy Snare. He too excuses himself, to go get some more booze, and he too is accosted by the boss. But this time Thanos gives his victim a drink and discusses strategy with him. He says that the fervour of the Magus' zealots makes him an even match now, but he will only grow in power as he gets more converts. So the tactic is to kill Magus' targets before they can *become* converts. The next race will be the peaceful Zen-Whoberis. Snare agrees with everything. Magus thanks him for his input and kills him for his lady Death, because it makes her appear more clearly to him. Butcher Squad here a scream and prepare for action tomorrow.
The troops approach Zen-Whoberi (which Gamora reminds us is her home) in Sanctuary's shuttle the Sepulcher. Thanos detects Magus' ships approaching as he drops bombs on the planet. We see young Gamora's family fleeing their home but her parents and brother die in front of her. Death watches her, and Thanos spies his love down there. Proxima informs him that Magus' himself is on Zen-Whoberi, and the Titan leads Aphaxia, Butcher and Crypt Squadrons down there.
After much bloodshed Magus confronts Thanos with his Black Knights. He has worked out Thanos' strategy but suggests that's not the only reason the Titan kills - but because it's the only thing that brings him peace. The Squadrons and Black Knights clash. Thanos remains in the thick of it but Magus stays out of the fighting. (I'm not sure he isn't just a hologram.) Thanos also eventually leaves the fight to go find Death.
He arrives at Gamora's house and finds the little girl hiding in a cupboard. She threatens him with a kitchen knife. He's about to kill her when he notices Lady Death is there, and Gamora pleads to her for help. But Death leaves them both. Thanos is shocked that someone else can see his love. (But Gamora's narration says that as the only survivor of her planet the little girl was bound to die soon, so *of course* she could see Death.)