The second novel in Doris Lessing’s Canopus in Argos science fiction series, The Marriages Between Zones Three, Four and Five, is marked out as different from the rest of the series by its fable-like qualities. The novel appears to narrate a quest for a kind of balance or harmony between the various Zones. This paper sets out to analyse the novel in relation to ecofeminist aesthetics, assessing what it is that Zones Three and Four learn from each other by tracing the relationship between Yori, a horse, and the queen of Zone Three, Al·Ith. Their relationship allows for a shift in the attitudes of both the king of Zone Four and Al·Ith herself, leading to the resolution of the novel, and the restoration of harmony to the fictional world Lessing creates. It is this shift that provides the focus for an assessment of the novel in relation to ecofeminist and ecocritical theory.