It’s the year 2005 and the Martin family has just received the latest household appliance, a NorthAm Robotics NDR-114 (ROBIN WILLIAMS), an anthropoidal robot designed for domestic chores. While Richard Martin (SAM NEILL) is excited about the family’s latest gadget, his wife (WENDY CREWSON) and two daughters, Grace (LINDZE LETHERMAN) and Amanda (HALLIE KATE EISENBERG) aren’t sure what to think of the "being" that Amanda nicknames "Andrew."
After Andrew details the three laws of robotics -- that a robot can’t purposefully or accidentally injure a human, that he must obey all human orders except when they mean certain harm to a human and that the robot must protect itself as long as that doesn’t come into conflict with the other laws - Richard decides not to activate the personality function, but instead allow Andrew to proceed as programmed.
Yet the family soon realizes that Andrew is more "human" than they initially imagined and they marvel at his woodworking skills and inquisitive nature. After Robert learns that NorthAm Robotics would like to dissect Andrew to find his "defect," he decides to become the robot’s tutor of all things human, ranging from humor to sex.
As time passes, Amanda (EMBETH DAVIDTZ), or "Little Miss" as Andrew still calls her, has grown up and Andrew has started a profitable business building old-fashioned clocks. Despite a fondness for each other, Little Miss marries someone else and Andrew, sensing a need to become completely free, leaves the Martin household, building a home for himself by the sea.
After many more years, Andrew sets out on a journey across the world in hopes of finding another robot like him. His decade long search eventually leads him back to San Francisco where he meets Galatea (KIERSTIEN WARREN), a somewhat flighty robot who’s been reprogrammed by Rupert Burns (OLIVER PLANT) to have something resembling a personality. While Andrew is disappointed to learn that he’s basically alone in this world, he’s encouraged by Rupert’s research that may allow him to physically become more human.
As Andrew reestablishes contact with the Martin family, this time with Little Miss’ granddaughter, Portia (EMBETH DAVIDTZ), he continues on his quest not only to look more human, but also eventually and officially be declared and accepted as just that by others.