In Nairobi, Kenya, 12-year-old Mungai takes a stand against the pollution suffocating the Nairobi River. Rallying residents of all ages, Mungai's grassroots movement gains momentum, catching the attention of even the Governor of Nairobi. Together, they lead the charge in cleaning the river, in unity of purpose to protect the environment. In the end, the river shines anew, a testimony of Mungai's unwavering dedication and the power of community action.