After news confirms the Undying alliance with Hevgoss, the Eternal Flame debates how to respond. General Hutchens argues that the alliance proves the obsidian offensive is working and urges a stronger attack before Hevgotian mercenaries arrive. Crowther warns that the Resistance lacks resources and that Hevgoss may increase nullium use or exploit whichever side wins, but Luc supports Hutchens and refuses Crowther’s proposal that he travel to Novis for diplomacy. Instead, Matias is sent to Novis with gold transmuted by Luc.

As the Resistance prepares for a desperate assault, Helena sees untrained civilians and children readying themselves with inadequate weapons and no armour. Believing the attack is suicidal without a decisive weapon, Helena goes to Crowther and proposes building a bomb that uses obsidian, and possibly nullium, to damage the Undying as their nullium bomb damaged the Resistance. Crowther is sceptical but agrees the design might be useful.

Helena is terrified that a successful attack could kill Morrough and destroy whatever sustains Kaine. She keeps the bomb secret from Kaine until the components are nearly complete, then asks him for a time and place where many Undying will gather. Kaine identifies an upcoming welcome banquet for Hevgotian officials and says he can use a stolen necrothrall to deliver the bomb, but he refuses to let Helena transport it because he remembers nearly losing her after the earlier bombing.

Helena and Shiseo assemble the bomb off-site, using difficult dual resonance techniques and designing it to explode without melting the obsidian. Helena burns her fingertips badly during the process, but hides the injury and later meets Kaine when he calls for her. During their stolen time together, Helena urges Kaine to run south if Morrough dies and Kaine survives, but Kaine refuses to leave without Helena and threatens anyone who would keep Helena from him.

Shiseo becomes the only practical choice to deliver the bomb. Before the delivery, Helena and Shiseo coat the bomb with mo’lian’shi and mirroring elixir to conceal it, and Helena similarly hides Kaine’s ring so it will be harder to detect if Helena is searched. Helena then visits Lila and feels the baby move, but Lila reveals that Luc has known about the pregnancy since Lila’s quarantine and made Lila keep it secret because he needed Lila to stay.

Shocked that Luc permitted Helena to care for pregnant Lila while forbidding Helena to treat Titus, Helena searches for Luc. Helena finally finds Luc in the hospital, guarded and resting, while Elain emerges with a tray of syringes and vials. Helena recognises dangerous combinations of medicines, including emergency injections from Helena’s own supply, and confronts Elain about overmedicating Luc, but Elain insists that she is Luc’s healer.