'The Expanse' Book 9 Titled 'Leviathan Falls,' Has 2021 Release Date

The ninth and final book of The Expanse series of science-fiction novels will be titled Leviathan Falls and will be released in 2021.

In a Wednesday live-streamed event over Crowdcast, The Expanse series authors Daniel Abraham and Ty Franck (who together write under the collaborative pen name James S.A. Corey) revealed both the title for the final book in the series and the cover, which portrays flames or an explosion gushing from one side of an immense spacecraft.

With art by Daniel Dociu and designed by Lauren Panepinto, the cover includes a pull quote from A Song of Ice and Fire author George R.R. Martin, who describes the book as "interplanetary adventure the way it ought to be written."

"This will be the last novel in the series, we are talking about putting together a collection of all of the novellas and short stories," Abraham said during the event. (The only exception to this proposed collection, according to the authors, will be a short story exclusive to the tabletop roleplaying game adaptation of The Expanse.)

The cover for 'Leviathan Falls,' the final novel in 'The Expanse' series. Orbit

The duo also took a number of questions from the live-stream's audience.

"There's no plan to write any more novels," Franck said, while emphasizing that he doesn't know the broader plans for the ongoing TV series. "There may be Expanse things, there just won't be the book version."

"No," and "Not a chance," the authors responded when asked if prequel novels were a possibility.

But while The Expanse book series may be approaching its end, it's not the end of their collaboration or the Corey pen name. The duo has already sold a three-book series to Expanse publisher Orbit.

"It's a very different project, though," Abraham said, contrasting it with The Expanse, which he described as following in the tradition of science-fiction authors Larry Niven and Alfred Bester. The new series apparently takes different inspiration, from authors who include more fantasy and mysticism in their work.

"I think Franck described it as 'the disappointing love child of Frank Herbert and Ursula Le Guin,'" Abraham said, naming the authors of Dune and The Dispossessed.

Even after Leviathan Falls comes out next year, fans of The Expanse will likely have a lot more to look forward to, including subsequent seasons of the critically acclaimed TV adaptation streaming on Amazon Prime Video. The fifth season of The Expanse, which is expected to follow the events of the fifth book, 2015's Nemesis Games, is expected to debut late in 2020.

The crew of the Rocinante will return in 'The Expanse' Season 5. Amazon Studios

"I'm reading a book right now that opens with a quote from Sophocles: 'One must wait until evening to see how splendid the day has been.' The end of a story is kind of the moment when you find out what the story has been the whole time," Abraham said of wrapping up The Expanse series, in an April interview for Tor.com. "When Ty and I started in on The Expanse, we had a mission statement in mind, and now we're going to get there and folks will be able to see what kind of project it's been. I'm looking quite forward to it."