After moving to the U.S. from his homeland of India, engineer Ben Jahrvi attempts to make a living in the big city peddling miniature toy robots, which he builds in the back of his truck. When one of Ben’s robots rolls through the office of toy buyer Sandy Banatoni, she offers to purchase 1,000 models for a major department store. Although Ben does not have the means to produce the toys in mass quantities, a sleazy con artist named Fred Ritter overhears the conversation and negotiates a deal to serve as Ben’s business partner. Fred obtains money from a loan shark, and leases a vacated warehouse to use as a factory. Meanwhile, two jewel thieves tunneling underneath the building worry that the business will thwart their plans to steal a case of valuable diamonds from the bank across the street. Hoping to drive them away, the criminals don masks and destroy all of Ben’s equipment. Dejected, Ben considers giving up the business until his friends, Stephanie Speck and Newton Crosby, send him a package containing the original life-size robot, Number Five, which Ben helped create. Fully sentient, the robot calls itself “Johnny Five” and offers to build the toys for their order. The next morning while Ben closes the deal with Stephanie, Johnny Five sneaks out to explore the city. The naïve robot is amazed by urban life, but addled by most residents’ rude and deceitful natures. Meanwhile, Fred conspires to sell Johnny Five, but the robot resists capture, and continues its efforts to assimilate into human society. Eventually, two police officers find Johnny Five wandering the streets and bring it to the station, where they lock it up with other stolen property. Learning of Johnny Five’s “arrest,” Ben rushes to the police station and retrieves the robot. Johnny Five explains that being treated like a subhuman machine has caused it to experience painful emotions, such as loneliness. Ben commiserates, sharing his own desire for companionship. Using information obtained from books about human behavior, Johnny Five offers to help Ben pursue a romantic relationship with Sandy Banatoni. Elsewhere, the jewel thieves team up with a greedy bank executive named Oscar Baldwin, hoping to use his budding friendship with Johnny Five to regain access to the warehouse tunnel. After kidnapping Ben and Fred, Oscar convinces the robot to finish digging until they reach the vault. When Oscar steals the jewels, however, Johnny Five realizes the trick and attempts to stop him. The thieves retaliate by attacking Johnny Five with an ax, leaving it severely damaged. Ben and Fred escape captivity, but police mistake Ben for the jewel thief and arrest him. As Johnny Five’s systems malfunction, Fred is forced to repair the robot himself. Although still leaking battery fluid, Johnny Five swears vengeance on Oscar, and chases his getaway car to the docks. Using its last remaining power, Johnny Five attacks Oscar and detains him until Ben arrives with police. Johnny Five’s memory drive fails, but Ben uses a defibrillator to revive it. Sometime later, Johnny Five gains national fame and becomes the first legally recognized robotic citizen of the U.S.