Twenty years after a ravaging war drastically transformed the face of the Earth, an old man and his energetic grandson Conan remain the sole survivors of their once larger community. Believing themselves to be the last humans on the planet, the two are surprised to one day discover a girl lying unconscious on the shore of their solitary isle. Once awakened, the girl Lana explains that she got lost while fleeing from agents of a technologized fortress island called Industria. Given that Lana is the telepathic granddaughter of renowned scientist Dr. Briac Lao, Industria's authorities desire her cooperation, as they believe her abilities will help them locate the doctor and acquire his expertise to access a powerful energy source. Despite the best efforts of Conan and his grandfather, they fail to prevent Lana's recapture when Industrian soldiers arrive. Vowing to rescue her, Conan bravely embarks on a breathtaking adventure, yet the journey comes with higher stakes than he realizes. [Written by MAL Rewrite]

Mirai Shounen Conan (Movie) is a summarized version of the television series, but made without the involvement of the series' director Hayao Miyazaki. Due to significant changes made to adapt the story into a two-hour movie and the use of a different soundtrack, the result was not well-received by fans. To promote the film, a "Conan Festival" was held at Nippon Budokan on July 20, 1979. Nippon Broadcasting System ran a four-hour live broadcast during its All Night Nippon program on August 31, 1979, featuring a live radio drama of the film with a newly written script. The voice actors also made guest appearances and interacted with fans by phone. On August 8, 2012, Mirai Shounen Conan (Movie) was aired on NHK BS Premium as one of the Summer Vacation Anime Specials. For this purpose, it was digitally remastered.