In the near future, industrial espionage of information systems is so rife, couriers have the information transmitted into implants in their brain that can hold gigabytes of information. Johnny Mnemonic is one of these couriers who's doubled his capacity to a dangerous 180 gigabytes and if he doesn't download in 24 hours, he'll die. Unfortunately, a gang of Japanese Yakuza mobsters are after what's in his head.