In the world of Johnny Mnemonic, computers and information are controlled by powerful corporations who rule over society. Johnny (played by Keanu Reeves) is a mercenary data courier who carries information illegally between clients. He has a special implant in his brain that allows him to store information beyond the capacity of regular computer networks.
One day, Johnny agrees to carry a package containing 320 gigabytes of data, which is far beyond the capacity of his implant. He is warned by his friend and surgeon, Spider (played by Henry Rollins), that the overdose of data will kill him if he doesn't remove it within 24 hours.
The package turns out to contain information that is far more valuable and dangerous than Johnny could have imagined. It is a cure for a deadly disease called Nascentia that is plaguing society. The cure is being suppressed by the ruling corporations who see it as a threat to their profits.
Johnny finds himself pursued by the Yakuza, a powerful Japanese criminal organization, and the pharmaceutical corporation that is trying to stop the cure from being released. With allies like Jane (played by Dina Meyer), a bodyguard who becomes his love interest, and J-Bone (played by Ice-T), a rebel leader, Johnny must fight to survive and remove the data before it kills him.
The film, released in 1995, was based on a short story by cyberpunk author William Gibson. It features a gritty, futuristic world that is still relevant today in its themes about technology, corporate greed, and the struggle for control of information.