Bone Season XVIII is the eighteenth Bone Season that took place in 2039. Paige Mahoney learned about the unspoken Bone Season from Liss Rymore, David, and Warden. She discovered the ruins with David that read: "For the Fallen, 28 November 2039." From this we can imply that the Bone Season XVIII rebellion occurred on this date.
On November 28, 2039, during Novembertide, a rebellion occurred in Sheol I where both humans and Rephaite rose up against the Sargas. Their plan was to kill Nashira Sargas and evacuate the humans to London. However, this goes awry when one human betrayed them, XVIII-39-7, by telling Nashira about their plan in exchange for his freedom. And thus, the rebellion failed and Nashira tortured the Reph perpetrators, letting the Emim slaughter all of the humans.
A group of Rephs also participated in the rebellion, and were therefore punished and referred to as "the scarred ones."
- Warden rebelled and suffers from permanent scars on his body from the rebellion. As such, he must take amaranth regularly to survive.
- Terebell Sheratan becomes known as one of the participants once Paige realized that Terebell has protected her and allied with Warden.
- Alsafi is never officially known as one of the rebels, although Alsafi revealed himself as an ally of Warden at the end of The Bone Season.