Affluent American homemaker Mary Morgan decides to withdraw her son George from school to educate him at home, which includes a journey to Southern Africa. During their stay in Mozambique, George is bitten by a mosquito that enters through a gap in his net, leading to his death from malaria. After returning home for his funeral, Mary feels compelled to go back to Africa, where she encounters Martha O’Connell, an Englishwoman whose 24-year-old son Ben, a volunteer teacher, also succumbed to malaria. Ben had given his mosquito net to a student, mistakenly believing that adults are not at risk of contracting the disease. The two women are appalled by the high mortality rate from malaria. While Martha remains in Africa to volunteer, Mary campaigns for the American government to take action. Martha unexpectedly visits Mary, and with the assistance of Mary’s father, a former diplomat, they present their case to a senate committee on health funding, urging increased efforts to fight malaria. They achieve some progress, although a final note indicates that much more remains to be done.