Born in 1930 to a recently widowed British-born mother on a farm in rural South Africa, P.K. leads a simple life initially learning the ways of England from his mother and the ways of Africa from his Zulu nanny (Nomadlozi Kubheka), whose son Tonderai is his best friend. However, everything changes for the worse when the cattle are struck down by plague, causing his mother to have a nervous breakdown. While his mother is recovering, PK is sent to an Afrikaner boarding school. Being the only English boy, he soon becomes the target of serious bullying: Fellow students claim to hold him responsible for the deaths of thousands of Afrikaners during the Second Anglo-Boer War and vow to punish him accordingly.
PK is victimised by all the boys at the school, but most of all by the older boys, led by a teen known as Jaapie Botha or "The Judge." In one incident, PK is urinated on by Botha and other students, earning the name "Pisskop" (pisshead in Afrikaans) and causing him to wet his bed often to avoid confronting the teens. Later when he goes home to attend his mother's funeral, he tells Nanny about the bedwetting. She arranges for the Zulu medicine man Dabula Manzi to come and cure PK of his bedwetting. Dabula Manzi helps PK to conquer his fears by leading him into the dreamworld (he touches the trunk of a charging elephant, causing it to be docile). PK is given a chicken, which he names Mother Courage, and becomes possibly PK's best friend he'll ever have during his childhood.
One day, PK is captured, along with Mother Courage, by the other boys and brought to a mock-trial by Botha, which reveals his new obsession with Hitler and the depths of his hatred for the English. First, Mother Courage is taken, hung from the ceiling by her feet, and killed. Enraged, PK lunges at Botha, knocking him backwards onto a small flag that pierces his buttocks, humiliating Botha when the other boys laugh at his pain and embarrassment. In anger, Botha orders PK to be hung in the same position as Mother Courage, where Botha attempts to hit him in the forehead with a rock from his sling. At that moment a teacher comes in, sees what's happening, and slaps Botha in the face, calling him a "dummkopf" (dummy). Afterward, Botha is expelled and reprimanded by his family.
With his mother and pet chicken both dead, and Tonderai and Nanny forced to return to Southern Rhodesia, the outlook seems bleak for PK. He finds himself alone and depressed in the world. Eventually, PK's grandfather arrives back from the Congo and PK goes to live with him in Barberton. However, as they fail to connect, his grandfather asks a friend of his to see him, a German pianist and amateur botanist, Karl 'Doc' von Vollensteen (Armin Mueller-Stahl). Like PK, Doc lost most of his family in Germany, and sees PK as a sort of replacement for his dead grandson. In time, Doc takes PK under his wing and provides him with piano lessons and begins to mentor him.
However, just as World War II begins, Doc is arrested and interned in Barberton Prison for failure to register as an enemy alien. The head of the prison staff, Kommandant van Zyl, a Boer who admires German culture, allows Doc to keep a cactus garden in the courtyard, his piano in his cell, and have unlimited visitation by PK. Doc is dismayed by PK's merely satisfactory marks at school, where smart kids are bullied, and arranges for him to be taught boxing by a Cape-Coloured prisoner named Geel Piet (Afrikaans for "Yellow Peter," played by Morgan Freeman). Geel Piet becomes another mentor for PK, training him to become an excellent boxer. Piet also teaches PK the mantra of "First with the head, then with the heart", an important phrase that will follow PK's life forever.
PK, now 12 (Simon Fenton), feels compassion and sympathy for the appallingly treated black prisoners. He and Doc supply contraband tobacco to Geel Piet for distribution to the other prisoners, and PK also becomes their unofficial letter-writer, treating all the tribes alike. As a result, many of the prisoners start calling PK "The Rainmaker." Almost at the end of the war, the Kommandant asks Doc to organise a concert to celebrate the annual visit by the prisons commissioner. At Geel Piet's request, Doc agrees, and the three scheme to create a concert based on subversive singing by the prisoners, whose lyrics indirectly insult and attacks the Afrikaner guards. On the night of the concert, PK is worried by Geel Piet's absence. When he sees a blood-spattered Sergeant Bormann appear at the fence behind the stage, PK runs off and finds Geel Piet lying near death in the yard, the victim of Bormann's bludgeoning. Geel Piet dies in PK's arms.
After the war's end, Doc is freed, but returns to his native Germany. In 1948, PK, now 18 (Stephen Dorff), is attending the prestigious Prince of Wales School in Johannesburg. He has won the respect of the school headmaster, Prof. St. John (Sir John Gielgud), who arranges a scholarship for PK due to his lack of funds. His best friend is his manager, Morrie Gilbert, who schedules boxing fights for him.
At the Johannesburg Schools Boxing Championship, PK sees an Afrikaner girl (Fay Masterson) in the audience whom he immediately fancies. Later, via Morrie, he learns that she is none other than Maria Elisabet Marais, daughter of the leading intellectual of the National Party, Prof. Daniel Marais, who is tipped to soon become head of government.
Since her father will not permit them to date (he disagrees with PK's views on apartheid), they do so secretly, and she accompanies him to the Alexandra township to a boxing fight against a black boxer, Gideon Duma (Alois Moyo). Even though Gideon loses the bout, Gideon and PK become good friends.
Duma's passion for resisting apartheid prompts PK to return temporarily to the African countryside of his childhood, inspiring him and Morrie to teach English to blacks. This, along with PK's romance with Maria, and his links with an unsegregated gym led by anti-racist Afrikaner boxing coach Hoppie Gruenewald, attracts the wrath of Dr. Marais. Marais requests that the head of the police, Col. Bratain, whose sergeant/aide is now PK's old enemy, Jaapie Botha (Daniel Craig) assign someone to spy on PK. Botha is assigned (or perhaps asks for) the surveillance job; he still blames PK for his expulsion from school.
At the same time, his blossoming relationship with Maria begins to deepen, in spite of her father's objections, but comes to a tragic end when, during a police raid on Morrie's uncle's Anglican church during one of the English lessons, Maria is killed by a blow to the head from a policeman's truncheon (an action he returns in kind by breaking a chair over the head of the officer responsible). Maddened with grief, PK considers leaving Africa to go to Oxford, but Gideon resurrects his spirits when he shows him the enormous difference that learning English is beginning to make to the people.
Events come to a violent climax that night when, searching for PK, Bratain and his police, including Botha, raid a party in Alexandra township. They enter in full force, indiscriminately shooting and bludgeoning people. As a deranged Botha prepares to shoot the boxing promoter, Elias Mlungisi, PK steps out of hiding, demanding that he end the raid. Both men square off and fight each other, with PK eventually knocking Botha out. As PK tries to care for Mlungisi, his back turned to Botha, Botha reawakens and attempts to shoot PK, but Gideon Duma appears and swings a cricket bat, smashing Botha in the head and presumably killing him.
The next morning, both men hide out in the scrubland as a Land Rover goes by loaded with police and then set off into the morning sunshine talking animatedly in Zulu with one another about their campaign against the regime, while in narrator voice PK identifies the various voices in his life, from his mother and nanny, to Doc and Dabula Manzi, and finally Maria.
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