Peter Jackson has not been attached to a major blockbuster film since the release of the third and final "The Hobbit" film. However, it has now been confirmed that his long-gestating film adaptation of "Mortal Engines" will be released on Dec. 14, 2018, but he is not in the director's chair.

According to Variety, Jackson will produce the film and write the script along with his long-time collaborators, Philippa Boyens and Jackson's wife, Fran Walsh.

Christian Rivers will be helming the movie, and this is noted to be his solo directorial debut. He previously worked on visual effects for "King Kong," and he also worked as a second unit director for "The Hobbit" trilogy and this year's "Pete's Dragon" remake. Rivers has been working with Jackson since the production of the 1992 film, "Dead Alive."

"Mortal Engines" will launch around the same as James Cameron's "Avatar 2" and "Mary Poppins Returns." It is also speculated that a "Star Wars" spin-off movie like the upcoming "Han Solo" from Lucasfilm will premiere in December 2018 as well, if it gets pushed from its May launch window.

The film will be an adaptation of the novels by Philip Reeve. In the books, the Earth has been ravaged by geological disasters and the war known as the "Sixty Minute War." To survive, several cities have attached large engines that allow an entire city to move around. These cities then travel to take resources from the cities that cannot relocate.

According to Cinema Blend, it is likely that Jackson's name will be used heavily during the marketing for the film even if he is not directing the project. The release date is also reminiscent of his past marketing decisions as "The Lord of the Rings," The Hobbit," and "The Lovely Bones" all premiered in the month of December.

No list of cast members has been announced yet, although the report states Jackson may cast a few high profile actors for the movie to compete against "Avatar 2."