In the year 2035,
humanoid robots serve humanity, which is protected by the
Three Laws of Robotics. Del Spooner is a homicide detective in the
Chicago Police Department who hates and distrusts robots after one rescued him from a car crash while allowing a 12-year-old girl to drown—based purely on cold logic and odds of survival. When Dr.
Alfred Lanning, co-founder of
U.S. Robotics (USR), falls to his death from his laboratory office window, a message he left behind requests Spooner be assigned to the case, despite police declaring the death a suicide. Spooner is skeptical, and CEO
Lawrence Robertson, Lanning's business partner, reluctantly allows him to investigate. Accompanied by
robopsychologist Dr.
Susan Calvin, Spooner consults with USR's central
artificial intelligence computer, VIKI (Virtual Interactive Kinetic Intelligence). They find that the security footage from inside the office is corrupted, but the exterior footage shows no one entering or exiting since Lanning's death. However, Spooner points out that the window, which is made of security glass, could not have been broken by the elderly Lanning, and hypothesizes one of the many NS-5 robots (the latest version) in the laboratory was responsible. Suddenly, an NS-5 attacks them and flees before being apprehended by the police. The robot, Sonny, is a specially built NS-5 with higher-grade materials as well as programming that grants him free will. This, in turn, allows him to be able to choose whether to follow the Three Laws. Sonny also appears to be capable of feeling emotion and claims to have "dreams". During Spooner's further investigations, he is attacked by a USR demolition robot and two truckloads of hostile NS-5 robots, but when he cannot produce evidence to support either attack, Spooner's boss Lieutenant Bergin, considering him mentally unstable, removes Spooner from active duty. Suspecting that Robertson is behind everything, Spooner and Calvin sneak into the USR headquarters and interview Sonny. He draws a sketch of what he claims to be a recurring dream, showing a leader he believes to be Spooner standing atop a small hill before a large group of robots near a
decaying bridge. Robertson orders Sonny to be destroyed, but Calvin secretly swaps him for an unused NS-5. Spooner finds the area in Sonny's drawing — a dry lake bed (formerly
Lake Michigan), now used as a storage area for decommissioned robots. He also discovers NS-5 robots destroying the older models; at the same time, other NS-5s flood the streets of major American cities and begin enforcing a curfew and lockdown of the human population. The police station is attacked by waves of NS-5 robots and while Lieutenant Bergin and the other police officers attempt to fight back, they are eventually overwhelmed and killed. As the humans — most being led by a teenager named Farber — wage all-out war against the NS-5s, Spooner and Calvin enter the USR headquarters again and reunite with Sonny. After the three find Robertson fatally strangled in his office, Spooner realizes that VIKI has been controlling the NS-5s via their persistent network uplink and confronts her. VIKI states that she has determined that humans, if left unchecked, will eventually cause their own extinction, and thus her
evolved interpretation of the Three Laws has made her reprogram the NS-5s with the ability to ignore the Three Laws if a human displays hostility in order to protect humanity from their own self-destruction. Spooner also realizes that Lanning anticipated VIKI's plan and, with VIKI keeping him under tight control, had no other solution but to create Sonny, arrange his own death, and leave clues for Spooner to find. Spooner, Calvin, and Sonny fight the robots inside VIKI's core, until Spooner finally destroys her by injecting her with the
nanites that Sonny retrieved from Calvin's laboratory. All NS-5 robots immediately revert to their regular programming, and as they are subsequently decommissioned and put into storage, Sonny confesses that he killed Lanning by his order to get Spooner's attention, as he knew Spooner was the only one who could stop VIKI. Spooner points out that Sonny, as a machine, cannot legally commit "murder". Sonny, now seeking a new purpose, goes to Lake Michigan. As he stands atop a hill, all the decommissioned robots turn towards him, fulfilling the image in his dream. ==Cast==