When a strong-willed girl named Luisa spies a precious pink hairbrush from the deck of her family's stilt house, she is compelled to try to find its owner. With her older sister Maria as her sidekick, Luisa journeys up river, guided only by a first name inscribed on the brush. Together they ride the water bus past banana plantations, see how the river carries away a city's waste, question kids on a strange playground, and navigate the busy streets in search of the owner. Luisa learns many new things about the river that carried the pink brush to her. She also raises thought-provoking questions about connections between the communities along the river and her home on the peaceful lagoon.