Told in the authors' alternating voices, Cleaving is both the story and the understory of a marriage, unique in its particulars but universal in its resonance. Childhood acquaintances, Vicki and Dennis meet again in their twenties and wed. Like many of their generation, they "promise each other nothing" and get more than they'd bargained for: alcoholism, infidelity, infertility, uncertainty. Gradually, tumult gives way to sobriety, parenthood, and meaningful work, but a sense of yearning remains.

In a quest to root themselves in the larger world, they embark on a mission to hand-drill water wells in Central America, attempting to slake a spiritual thirst by addressing a practical need.