Leviathan Falls is a science fiction novel by James S. A. Corey, the pen name of Daniel Abraham and Ty Franck, and the ninth and final book of the series The Expanse.

[4] Following the events of Tiamat's Wrath, the mysterious "dark gods" or "ring entities" have been experimenting with methods to kill humans in various ways, including adjusting the principles of physics in some systems, and launching their loss-of-consciousness attacks.

Winston Duarte suddenly awakens from his semi-catatonic state with newfound knowledge about the Ring-Builders, and new abilities, including being able to project a vision of himself into other people's minds.

Upon arrival, Duarte has already disappeared from the state building, and Colonel Aliana Tanaka is tasked to locate him with the highest possible level of security clearance.

Tanaka's search leads her to the cave Amos Burton once inhabited, where she deduces that Duarte left Laconia in a small alien ship.

They transit to the colony world of New Egypt to take Teresa to a boarding school near her relatives, but they find Tanaka and a team of Laconian marines already waiting for them.

This event causes the rings to glow brightly and triggers those in the slow zone and aboard the ship to begin to experience shared memories.

During this process, the vision of Duarte appears to Elvi and Holden, proposing that humanity must join him in creating a hive mind to counter the ring entities' attacks, just as the Ring-Builders had.

She learns that Laconian scientists believe they have found Duarte's alien ship on the surface of the Ring Station, and both the Rocinante crew and Tanaka decide to head there.

Meanwhile, a massive space battle unfolds in the slow zone, as the joint underground and Laconian fleets desperately tries to buy Holden and Tanaka time despite heavy fire from Duarte's hive mind controlled ships.

While they journey through the station, Miller explains that the Ring-Builders had discovered that the universe existed alongside a much older parallel reality, and built the slow zone within this alternate realm, using the immense energy of the other dimension to power the gates.

Alex takes the Rocinante to Nieuwestadt system to live with his son and grandchild, while Amos, Naomi, and Teresa travel with Elvi back to Sol.