At the height of the British Raj, Major Francis Browne, British Resident in the Princely – semi-autonomous - State of Jerupore, is travelling with his family across the burning Rajasthan desert, when his only surviving child Emily falls gravely ill. At the point of death, she revives when an enigmatic Hindu saddhu, Shiva Singh, comes to treat her. Francis dismisses this as mere coincidence, but his wife Louise believes the sadhu has saved Emily's life, and wonders if he could also cure her of the barrenness that has afflicted her since Emily’s difficult birth.

Shiva Singh is a radical sadhu, a Brahmin who denounces the caste system and the priesthood and calls for a 'purification' of Hinduism. It is for this reason that a young Brahmin girl, Nirupama, who has narrowly escaped being killed by her family for loving a lower-caste man, becomes one of his most devoted followers.

Shiva’s growing influence among the lower castes and dispossessed infuriates the upper castes in the state, who see a threat to their power and privilege. There is a danger of unrest and riots, which concerns the Resident as much as the Maharaja's advisers. At the same time, Louise Browne longs to meet the sadhu again and seek his help, although Francis warns her not to, and in any case Shiva remains upcountry, far from the capital. When she unexpectedly meets the Indian woman who was her husband's mistress and has borne his child, however, Louise resolves to disobey him.

Shiva Singh comes to the city of Jerupur at last and Louise goes secretly to hear him speak. Immediately afterwards, upper caste men attack the sadhu's followers, and in the ensuing riot, both Nirupama and one of the attackers are killed. Shiva Singh is arrested on a trumped up charge of murder. The Maharaja wants him tried in Jerupur, but for that he needs the Resident’s consent, for Shiva is a subject of British India.

Convinced he has committed no crime, Major Browne at first refuses, believing the sadhu is innocent and knowing he will certainly die if he is tried in Jerupur. But the Maharaja has information with which he can blackmail him, and rather than be disgraced, the Resident surrenders, despite the reproaches of his conscience and the frantic protests of his wife.

The sadhu is quickly tried and executed in the traditional manner, trampled by an elephant. But widespread revulsion against the barbarity of his execution leads the Viceroy to replace Major Browne and arrange for the Maharaja to be deposed. In their new, lower, post, Louise bears another son, and reveals to her husband that the sadhu had assured her she would do so. But there is another, stranger, revelation that is gradually borne in upon the reader as the story progresses : Shiva Singh’s life seems uncannily like that of Christ – and the sadhu seems to have known it would be.