The film takes place in Johannesburg in 2016 where crime has become so out of control that the human police force must be supplemented by a collection of nimble, blue robots called "Scouts." The crime rate plummets quickly, and within a year of the robot police program's inception, 20 of the city's major gangs have been eradicated.
This is the story of one of those robots. Its serial number is 0022. It has bad luck, having been run over by a vehicle when we first meet it and received a direct hit from a rocket during a raid on one of the city's gangs.
Deon Wilson (Dev Patel), the man responsible for creating the Scouts, wants to save this robot for an experiment in artificial intelligence. He believes he has found the coding that will enable a computer program to become sentient—to learn, feel, and express itself in a way that is distinctly human. The gang captures Deon, believing he holds the key to deactivating all the robot cops.
A turning point occurs when Deon uploads his artificial intelligence program into the robot. He informs the gang members that it's going to take some time for the robot to learn—that it will first seem to have the brainpower of a super-intelligent human baby. When Chappie (Sharlto Copley)—as it boots into existence, it huddles in a defensive pose and scurries into hiding. The rest of the movie is about how Chappie grows from the pure innocence of his nature into an entity that is trying to figure out who it is by way of the nurturing of his loving mommy, his corrupting "daddy" (Ninja), and his rule-bestowing "maker."
Chappie is an allegory, a fairy tale, and a study of an entity's psychological development. But, just when the movie seems to be hitting its stride, director Neill Blomkamp falls back on the reliable and the expected. This is a movie that dares to raise the big ideas, only to cower into a comfortable corner whenever the time comes to actually address those concepts. Chappie leaves us wanting much more.