Eight-year-old Law Chun-yi lives with his parents and his sixteen-year-old brother Desmond in a shoe shop on Wing Lee Street in late 1960s Hong Kong. Chun-yi looks up to his brother, who is a champion runner at the prestigious Diocesan Boys' School, earns top grades, is a talented musician, and is very popular; Chun-yi's parents and teachers often scold him for his poor attitude in learning. Desmond has a girlfriend, Flora, who comes from a wealthy family. Flora's family moves away from Hong Kong to the United States, affecting Desmond's grades and performance in school. He also gradually becomes aware of the inequalities in Hong Kong society of that time, both through interactions with a cocky British policeman who extorts money from his father in exchange for letting them keep their shop and through his first time seeing the inside of Flora's family's mansion. Most of this is told through Chun-yi, the film's narrator. Not long before Flora leaves, Desmond's grades start declining and he takes third place in a race he had hoped to win. One day he collapses suddenly after a typhoon nearly destroys the family's house, and his father takes him to the hospital, where he is diagnosed with leukemia. His parents search for a doctor who can cure him but find none, and his condition worsens until he has to remain in the hospital, where the nurses treat him poorly and extort money from his parents in exchange for basic care. Chun-yi, who spends much of his free time stealing trinkets around town, tries to offer them all to his brother in attempt to cheer him up, but Desmond doesn't accept any of them. Flora returns from the United States and visits him in the hospital, where they share their first kiss, but Desmond dies shortly thereafter. Years later Chun-yi, narrating retrospectively, remarks that "time is the greatest thief". In the film's final scene, Chun-yi and his mother are shown visiting Desmond's grave, and Chun-yi, now a teenager, recounts a lesson Desmond had taught him about double rainbows.
China Daily placed the film on their list of the best ten Chinese films of 2010. Wing Lee Street, where Echoes of the Rainbow was shot, was originally included in a redevelopment plan. However, the Berlinale award won by the film stimulated the wish of Hong Kong people to preserve this heritage site and community. The Town Planning Board eventually decided to keep all the tong laus on the street and to designate the region as a preservation site.
