The film centers around two brothers, Damian and his older sibling Anthony. Their personalities starkly contrast; while Anthony is driven by a desire for wealth and attention, Damian takes a different path influenced by his admiration for good deeds following their mother's passing. He secretly believes that she might be a saint.
After relocating to a new housing development, Damian finds joy in creating a small fort out of cardboard boxes. One fateful day, a duffel bag filled with cash crashes into his fort as a high-speed train rushes by. Anthony seizes the moment, showing the windfall to Damian, who interprets this as a divine blessing.
With their unexpected wealth, the brothers embark on their separate journeys of spending. Anthony quickly uses the money to buy items and garner peer recognition at school, while Damian endeavors to make a difference, even treating homeless people to pizza with some of the cash.
One afternoon, Damian notices a man rummaging by the train tracks and, upon learning the man is poor, hastily runs home for money. However, Anthony accompanies him and decides to give the man a jar of coins instead. This act of generosity earns Damian a lecture from Anthony about being reckless.
The urgency of their situation escalates as the United Kingdom prepares to transition from British pounds to Euros. Anthony tries to deposit their newfound fortune in a bank, but without an adult present, they hit a dead end. Meanwhile, a woman named Dorothy, who visits their school to solicit donations for well-building initiatives in Africa, unwittingly adds to their dilemma when her remote-controlled 'bin' finds its way to Damian, who donates 1,000 pounds.
As the plot thickens, Anthony’s classmate reveals a heist involving the train transporting old pound notes to be destroyed, making Damian realize the origin of their windfall. However, he’s soon called to the headteacher's office alongside Anthony and their father to discuss the donation. Anthony concocts a tale about how they acquired the money from some Mormons in the neighborhood.
The situation grows more tangled when their father talks to Dorothy, who needs help with her robotic 'bin.' When the boys attempt to take back the extra cash for deposit, Anthony covers their tracks by claiming they are rehearsing for the school play, leading to a tight grip on their duffel bags full of cash.
During the Christmas play, Damian spots the man he had previously seen by the tracks. Alarmed, he flees the performance with the money and seeks refuge in their old house. There, he confesses to his father about the money's discovery, explaining that he thought it was a gift from God.
Upon returning home, they discover their house has been ransacked, likely by the 'poor man.' The boys' father decides to use what little remains of the money, despite Damian's insistence that it's morally wrong. Upset and troubled by his Dad's decision, Damian falls asleep, only to be visited in his dreams by the 'poor man,' who assures him he will return the following day.
The next day brings a revelation; with Dorothy in the loop, the family ventures into town, exchanging their pounds for Euros. Though they spend some money, a portion remains. As they celebrate, Anthony feels jealousy towards Dorothy's growing closeness with their father and unfairly blames Damian.
Feeling lost, Damian departs with the duffel bags. Back at home, several people arrive, requesting assistance from their father, while the 'poor man' is apprehended by the police. In a desperate act of closure, Damian takes the remaining cash to the train tracks and ignites it.
As a train comes barreling by, Damian spots a woman across the tracks, whom he instinctively recognizes as his mother. In a moment of reflection, she imparts wisdom, revealing that she has attained sainthood, and that her miracle lies in him. This touching encounter is brief, as Anthony catches a glimpse of the vision before it fades away.
The next day, Damian comes clean about burning the cash, but it's revealed that he and Anthony had also hoarded some bills, which weren’t destroyed. The story concludes with a fantastical journey where Damian, Anthony, their father, and Dorothy travel to Africa, using the remaining funds to support the charity's mission of establishing wells in villages.
