Schoolboy William Kamkwamba (Maxwell Simba)hails from a family of farmers live in the nearby village of Wimbe. William loves fixing radios for his friends and neighbours and spends his time looking through the local junkyard for salvageable electronic components.

Due to his parents' inability to pay his tuition fees, William is barred from attending school. William blackmails his science teacher into letting him continue attending his class and have access to the school's library where he learns about electrical engineering and energy production.

During the mid-2000s, saw failing crops due to a drought and with the resulting famine has devastated William’s village, leading to riots over government rationing and William's family being robbed of their already meagre grain stores.

People soon begin abandoning the village, and William's sister elopes with his former teacher in order to leave her family "one less mouth to feed".

William devises a plan to build a windmill to power an electric water pump as he seeks to save his village from the drought. William builds a small prototype which works, but to build a larger windmill, William requires his father, Trywell (Chiwetel Ejiofor), to give permission to deconstruct the family bicycle for parts, which is the only bicycle in the village and the family's last major asset.

William's father believes the exercise futile and destroys the prototype. However, after intervention from William's mother, William and his father reconcile, and with the help of his friends and the remaining members of the village, they build a full-size windmill which leads to a successful crop being sown.