In a futuristic setting, the stunning Barbarella (Jane Fonda), an adventurer who specializes in astronomy, finds herself journeying through the cosmos aboard her spacecraft, the Alpha-7. Out of the blue, she receives an urgent communication from the President of Earth (Claude Dauphin), who informs her of a crucial mission. A brilliant scientist, Durand Durand, has vanished during a mission to the North Star, and it is suspected that he may have crash-landed somewhere within the enigmatic Tau Ceti star system. The President expresses his deep concern that Durand's groundbreaking invention, the positronic ray, could be seized by a primitive culture that might misuse it for warfare, posing a threat to the peaceful existence of Earth.
Tasked with this perilous mission, Barbarella receives some weaponry and a language translation device, known as a tonguebox, which will aid her in communicating effectively during her journey. After engaging in suspended animation during much of her flight, Barbarella awakens just in time to realize that her ship is out of control, leading to a crash landing on Planet 16. The planet exhibits an atmosphere reminiscent of Earth, prompting Barbarella to don a new outfit for exploration.
Her initial encounters reveal two energetic twin girls who speak an unfamiliar language, leaving Barbarella perplexed. Before she can make sense of the situation, one of the girls knocks her out with a chunk of ice, leading to her being dragged away on a sled, pulled by a graceful creature that glides effortlessly over the icy terrain. When they arrive at the wreckage of another spacecraft, Barbarella discovers it to be none other than Durand Durand's former vessel, the Alpha-1. The twins, joined by other children, mischievously bind Barbarella to a post, provoking mechanical dolls equipped with sharp metal teeth to approach her, creating a surreal and frightening scenario.
A heroic figure soon emerges—Mark Hand (Ugo Tognazzi), a Catchman, accompanied by several guards. Demonstrating bravery, he subdues the children and rescues Barbarella, explaining that he captures children to send them to the this area's forests "until they've reached a serviceable age." He subsequently offers to escort her back to her ship, and when Barbarella inquires how she can repay him, he expresses a desire for intimate relations. In their advanced society on Earth, people engage in physical bonding through an exultation transference pill, but Mark proposes a more traditional approach. Though hesitant, Barbarella finds herself enjoying the experience.
Mark helps repair her damaged spacecraft, but when she attempts to take off, she discovers that the repairs were mistakenly made in reverse, causing her to crash once again. In a determined bid for survival, she engages the ship's terra-screws to tunnel through the planet's core and pops up in the Labyrinth. Here, she meets Pygar (John Phillip Law), an angelic figure who has been rendered blind. He introduces Barbarella to Professor Ping (Marcel Marceau), who shares that the Great Tyrant has condemned Pygar and others to the Labyrinth.
Taking Barbarella to his nest, they engage in an intimate encounter that restores Pygar's lost ability to fly. Together, they soar towards Sogo, but their journey is interrupted by an assault from the Great Tyrant's black guards, a confrontation they manage to overcome. Upon entering the decadent city, Pygar's wings draw unwanted attention, leading to his capture. Barbarella is nearly assaulted by two ruffians but is saved by a woman with an eyepatch who becomes enamored with her.
In a twist of fate, Barbarella and Pygar find themselves whisked away to the ominous Chamber of Ultimate Solutions. Discovering the lurking threat of the Mathmos, a malevolent force, they narrowly escape, but not before Barbarella has a fateful interaction with the Concierge of the Great Tyrant (Milo O'Shea). He confines her within a glass cage teeming with small birds intent on tormenting her, but she soon finds herself plunging into the Rebel headquarters.
Leading the resistance is Dildano ([David Hemmings]), who devises a plan against the Great Tyrant to restore peace to the city. Together, they formulate a strategy, although Dildano shuns traditional sexual practices in favor of utilizing the more civilized Earth method. After a series of unexpected turns, Barbarella unwittingly finds herself re-encountering the Concierge, who confiscates her means of escape and locks her with the sleeping Great Tyrant. The situation escalates, culminating in resistance efforts clashing with the Great Tyrant’s forces.
As the battle unfolds, the evil Mathmos is unleashed, wreaking havoc upon all who dwell within the city, while Barbarella and Pygar represent the last bulwark against destruction. In an act of benevolence, Pygar carries them both to safety, embodying the notion that “an angel has no memory,” highlighting the deeper themes of love and redemption resonating through their fantastical journey.
