Jens, a 16-year-old boy, embarks on a camping adventure with his friends at a secluded cabin. Among them is Lisa, played by Ingrid Bolsø Berdal, who was Jens’s crush from the previous summer before moving away due to her father securing a new job in Oslo. The trip takes a romantic turn during a game of Truth or Dare, when Jens is dared to kiss Lisa, leading to a moment that sparks their intimacy. Later that night, Jens and Lisa share their first sexual experience, an event that becomes a pivotal moment in their journey.
Unbeknownst to them, inside Jens’s testicles resides a tiny society of sperm cells, each with unique personalities and ambitions. Among them is Simen Sprut, a young sperm cell who stands out because of his disinterest in racing toward the egg, which causes him to be ostracized by the others. His only ally is Cumilla, a fellow sperm who tries to motivate him to participate in the race toward fertilization. Meanwhile, a high-tech sperm cell named Jizzmo, an ambitious and inventive entrepreneur, crafts an armored suit called the Ejaculator 9000, designed to help him dominate the competition by overcoming any obstacle—including deadly fights with rival sperm.
During Jens’s first ejaculation, Jizzmo makes a daring move by cutting open the condom, allowing himself and other sperm to enter Lisa's body. During this process, Simen accidentally holds back Cumilla, causing tension among the sperm. As Jens and Lisa have sex again, things take an unexpected turn when Jens, fatigued and with bruised eyes from earlier, unintentionally penetrates Lisa anally. This unconventional encounter results in Simen, Cumilla, Professor Saltsmak, and a classmate called Etterskvett entering Lisa’s urinary tract, only to end up in her rectum. There, they encounter an E. coli bacteria that guides them through Lisa's system. The sperm swim through her bladder and manage to navigate onto her pubic hairs during urination, only for Etterskvett to fall to his death in the process.
Lisa, aware of the sperm invasion, applies spermicide to her uterus, which kills many sperm, including Professor Saltsmak. Meanwhile, a group of gangsters led by Egon Olsæd, who are on a ruthless mission to reach the egg and become triplets, attempt to get the spermicide to eliminate Jizzmo. However, Jizzmo narrowly escapes and causes chaos—killing Egon’s allies Benner'n and Bjell. Jizzmo’s aim is to wipe out all competing sperm, but Egon intervenes, causing Jizzmo’s armor to self-destruct in a heroic sacrifice that destroys the spermicide and allows the remaining sperm, including Jens’s friend Simen and Cumilla, to continue their journey toward the egg.
Later, Jens and Lisa go for a walk, where Lisa expresses her frustration about not reaching climax during their encounters. The couple then has sex against a tree, and as Lisa ejaculates, a falling beehive lands on Jens’s pelvis, prompting him to ejaculate into it. The bees chase Jens and Lisa, leading to a fall down a hill. Inside Lisa’s uterus, the chaos causes the egg to bounce unpredictably, killing off nearly all the sperm cells except for Simen and Cumilla. Just as they approach implantation, Jizzmo, still alive, attacks them but is ultimately defeated when he bites off Cumilla’s tail and gets crushed by the egg.
In the culmination of their journey, Simen and Cumilla manage to enter the egg together, securing their chance at fertilization. Six weeks later, Jens and Lisa visit a clinic to discuss pregnancy options. The gynecologist explains through song that taking time to plan for a family is important if they decide to proceed, emphasizing thoughtful decision-making. The film concludes with Jens suggesting a movie marathon with Lisa, as the abortion pill they are considering will take two days to become effective.
This animated expedition blends humor, biology, and adventure to depict the microscopic battle inside the human body, illustrating the complexities of conception with a unique and detailed perspective.
