Tanjiro and Inosuke battle the Demon Slayers trapped by spider webs. After slashing the threads and destroying the webs, they head deeper into the mountain. The farther they advance through the forest, the thicker the threads become, and those under their control start moving in ways impossible for a human being. Stopping the Demon Slayers without hurting them isn't going to be easy, but then Tanjiro makes a certain move...
Murata volunteers to hold off the controlled slayers so Tanjiro and Inosuke can go after the Spider Demon Mother. The two are intercepted by a female controlled slayer, Ozaki, who begs them to summon more help, having been controlled to kill some of her comrades.
As Mother controls the Slayers to her will with her threads. Rui appears before Mother and tells her she better hurry before he tells Father and she, terrified, begs him not to tell Father.
Mother starts controlling Ozaki's body so hard the movements break her bones. Another Slayer begs Tanjiro and Inosuke to kill him, as all his limbs are broken and he also has severe inner wounds.
Tanjiro tackles Ozaki and throws her into the branches, tangling her so she can't fight and Inosuke follows his lead. As they go to tangle the last one, Mother angrily breaks all of their necks angering Tanjiro. Unable to do anything, the two continue struggling. Zenitsu, meanwhile, wanders around the mountain, calling for Nezuko.
A massive headless demon doll with blades for arms suddenly intercepts Inosuke and Tanjiro. Inosuke charges and is almost killed until Tanjiro saves him. Working together they hack the massive doll to pieces and it dissolves. Inosuke throws Tanjiro into the air, sending him hurtling towards Mother.
From her spot, Mother sees him falling from the sky about to use the Water Breathing, First Form: Water Surface Slash and initially panics... but realizes she'll be released from Rui and Father's threats if he kills her and lets him strike her down. Tanjiro realizes this and, since Mother is surrendering, he then uses the Water Breathing, Fifth Form: Blessed Rain After the Drought, beheading her with no pain. As thanks for the peace of death, and also recalling her unfortunate life as a Spider Demon, the Mother Spider Demon warns Tanjiro one of the Twelve Kizuki is on the mountain.