The River and the Source traces four generations of Kenyan women through more than a hundred years of their country’s history. It begins roughly in the year 1870 when Akoko is born in the Luo village of Yimbo, where life is ruled by tradition. The daughter of chief Odero Gogni, Akoko marries Chief Owuor Kembo, who pays an unheard-of thirty head of cattle for her bride price. Owuor and Akoko are happy together, but over the course of their marriage, Akoko begins to push back against her in-laws' limited ideas of a woman’s worth. Akoko has two sons, Obura and Owang', and one daughter, Nyabera. Both of her sons as well as her husband eventually die, and Akoko must find the strength to persevere. Breaking tradition, she ultimately decides to leave her husband's compound and return to her ancestral home.
Akoko’s daughter Nyabera also loses her husband and all but one child to illness. Searching for hope, she hears of a new religion brought by the white colonialists and decides to leave her village and make a new life for herself at the Catholic missionary. Eventually she convinces her mother Akoko, as well as her daughter Awiti and nephew Owuor, to move with her and they all make a life for themselves there. Awiti excels at the mission school and with the support of her mother and grandmother continues her education until she becomes a teacher, an unusual path for a woman of her time. Her cousin Owuor is the rightful heir to become chief in Sakwa, yet he feels called to become a priest. Akoko accepts his decision despite how hard she fought for his inheritance. Owuor goes on to become a priest and then bishop.
Awiti, who takes the name Elizabeth after going to college, meets Mark, a Luo man from the town of Seme, and the two begin a relationship. But before they can get married, Akoko passes away. After a period of mourning, the two marry and have seven children. During this time, Kenya gains independence from the British in 1963. Elizabeth and Mark have twins, Becky and Vera, who are complete opposites: Becky is beautiful and selfish and Vera is intelligent and motivated. Growing up, Vera is deeply loyal to her sister until she becomes tired of Becky’s self-absorbed attitude. The sisters fight and are never fully able to repair their relationship. Vera heads off to university while Becky runs away from home to become a flight attendant. Becky shocks her family by marrying a white man; Vera decides to devote her life to work and God, choosing never to marry.
Aoro, the eldest son of Elizabeth and Mark, heads off to medical school where he meets Wandia. The two are highly motivated students and compete before eventually dating and getting married. Living in a rapidly modernizing Kenya, both balance their careers as doctors with raising a family. Wandia integrates herself into the network of strong women in Aoro’s family who are carving out places for themselves in society. Wandia and Aoro have four children together and adopt Becky’s two children after she dies of AIDS. The story closes with the family mourning Elizabeth/Awiti. At her funeral, the family members linger by her grave until one by one they are pulled back into life, and as the novel suggests, they must continue on with their lives.
