Intercepting the transport carrying Foundation X’s new 2nd generation Gaia Memories, the special-ops unit NEVER, led by Daido Katsumi, intend to turn Fuuto into Hell on Earth. With Daido wielding the T2 Eternal Memory and a Lost Driver, granting him power in the form of Kamen Rider Eternal, Fuuto’s Kamen Riders are left powerless as Daido and his allies take control of Fuuto Tower, converting it into a massive laser weapon…

Movie War 2010 is split into three parts. The Kamen Rider Decade portion of the film, written by Shoji Yonemura, is titled Kamen Rider Decade: The Last Story. It follows the series cliffhanger ending at the climax of the Rider War. The film is billed as the "True Ending" and was originally subtitled Decade vs. All Riders. The Kamen Rider W portion of the film, written by Riku Sanjo, is titled Kamen Rider W: Begins Night, taking place between episodes 14 and 15 of Kamen Rider W, investigates the origins of Kamen Rider Double as briefly shown in the cold opening of the series' first episode, referred to in the series as the "Begins Night". The film is described as the "True Beginning" and was originally subtitled Episode Zero. In the final portion of the film entitled Movie War 2010, a convergence of the two films that brings the casts and characters of Decade and W to finish the fight with Super Shocker together.

Set primarily before the events of Kamen Rider W Forever, Kamen Rider Eternal tells the story of Daido Katsumi, the formation of NEVER, the mission that led them to target Fuuto, and reveals just how Daido obtained his Lost Driver and got his first taste of the power of Kamen Rider Eternal. As a mysterious woman retells this story to Phillip and Shotaro, they realize that Daido may not have been the simple monster he first appeared to be…

While settling into married life with Akiko, Ryu is brought into a case involving a woman named Katsuragi Aoi, a member of a pickpocketing ring with most of her teammates murdered from unknown masked vigilantes that Ryu fought as Accel. As the details of the case begin to unravel, Ryu is framed and Akiko believes that he may not be faithful to her. As the clock ticks down, Ryu must solve the case, clear his name, and save his marriage before everything comes to an explosive end!