In the summer of 1965 in the Australian mining town of Corrigan, 13-year-old Charlie Bucktin is surprised late one night when Jasper Jones shows up with promises of taking him to see something very special out in the bush. Jasper has a bit of a rebellious streak that Charlie finds intriguing. Of course, it’s not all Jasper’s fault; rebellion is a natural reaction to being deemed an outcast simply because, like Jasper, your blood is mixed with the heritage of the indigenous Aborigines and the whites who showed up to take over their land. On this particular evening, Jasper seems a little overstimulated compared to his usual state of mind, however, and when Charlie follows him to his secret glade in the bush, he finds out why: the dead body of Jasper’s girlfriend, Laura Wishart, is hanging from a tree. And from the looks of it, she was beaten before being hanged.
Jasper’s unexpected arrival served a purpose: he needs Charlie’s help in burying the body. And he knows he must dispose of the body because otherwise he will get the blame and bear the brunt of the punishment. Together, the two boys manage to sink the corpse to the bottom of a reservoir with a big rock serving as its anchor.
It doesn’t take long for the town to realize that Laura has gone missing, and though most assume she ran away, a search is organized. The police, as expected, target Jasper for intense interrogation of a typically excessive nature, but he is eventually released. Even so, a bitter sort of energy is becoming almost palpable throughout the town as they look for someone to blame in the face of their fear that Laura won’t be the last victim.
Charlie deals with his emotional turmoil by playing cricket with his best friend, Jeffrey Lu. Jeffery is from Vietnam. Jeffrey, like Jasper, has had more than his share of dealing with suspicion and paranoia bred by racial intolerance, for example when he tried out for a spot on Corrigan’s cricket team only to have it made abundantly clear that he wasn’t welcome. Cricket becomes a source of relief for both Charlie and Jeffrey as Jeffrey becomes the hero of the game at the exact moment that Charlie has his first kiss with Laura’s younger sister, Eliza.
Meanwhile, Jasper has become convinced that a weird old guy who lives alone amid rumors of a dark past is the person responsible for killing Laura. Jasper convinces Charlie to accompany him to Mad Jack Lionel’s house only to come face to face with an entirely different conclusion: the old man is Jasper’s own grandfather and that dark past involved accidentally killing Jasper’s mom while speeding in an effort to get her to the hospital before she gave birth. Like his grandson, Mad Jack Lionel has been ostracized by the community.
Another late night, another unexpected visitor for Charlie. This time it is Eliza, and he accompanies her out to Jasper’s glade. While there, Charlie learns the truth about what happened the night Laura died. Eliza explains how her sister got into a terrible fight with their dad before running away to find Jasper. Eliza decided to follow her to the glade and watched as her sister, pregnant with a child by her own father, killed herself. Eliza, in great distress, confesses that she tried to save her but failed. Charlie is then moved to make his own confession about what he and Jasper did with her body. The very same night, they both spy Charlie’s mother making out inside a car with a man who isn't her husband.
Charlie decides not to leave Corrigan as planned, but has no qualms at all about his mother deciding to hit the road. Eliza shows the suicide note Laura left to her mother as proof of just how abusive their father really is and warns that if she decides to do nothing about it, she won't ever tell her mother where Laura's body lies.
Telling no one, Jasper also leaves town. Only Charlie seems to notice his absence.