In a future society governed by eugenics, where potential children are conceived through genetic manipulation to ensure they possess the best hereditary traits of their parents, Vincent Freeman is conceived naturally and born with a heart condition that would cast him as a second-class citizen. His parents, realizing the disadvantages he will have to face, have another child through genetic selection. Vincent grows up with the constant reminder of his genetic shortcomings and society's preference for the genetically enhanced, including his nearly perfect brother, Anton. Despite his passion for space travel and a seemingly unattainable dream to work at Gattaca Aerospace Corporation, Vincent’s flawed genetics deny him any chance of a professional career. His determination leads him to a black market where he can purchase the genetic identity of Jerome Morrow, a former swimming star with a perfect genetic profile who has been paralyzed due to an accident.

Vincent assumes Jerome's identity and is able to secure a position at Gattaca, adhering to a strict regimen of physical conditioning and extensive personal grooming to avoid shedding any trace of his original DNA. He meticulously uses Jerome's hair, skin, blood, and urine samples to pass the rigorous daily checks at work. Meanwhile, he forms a complex relationship with coworker Irene Cassini, who harbors her own genetic secrets. As Vincent gets closer to achieving his dream, a murder at the corporation threatens to expose his true identity, placing his meticulously constructed life in jeopardy.