Thomas Hart and Grace Macauley are fellow worshippers at the Bethesda Baptist chapel in the small Essex town of Aldleigh. Though separated in age by three decades, the pair are kindred spirits - torn between their commitment to religion and their desire for more. But their friendship is threatened by the arrival of love.

Thomas falls for James Bower, who runs the local museum. Together they develop an obsession with the vanished nineteenth-century female astronomer Maria Veduva, said to haunt a nearby manor, and whose startling astronomical discoveries may never have been acknowledged. Inspired by Maria, and the dawning realisation James may not reciprocate his feelings, Thomas finds solace studying the night skies. Could astronomy offer as much wonder as divine or earthly love?

Meanwhile Grace meets Nathan, a fellow sixth former who represents a different, wilder kind of life. They are drawn passionately together, but quickly pulled apart, casting Grace into the wider world and far away from Thomas.

In time, the mysteries of Aldleigh are revealed, bringing Thomas and Grace back to each other and to a richer understanding of love, of the nature of the world, and the sheer miracle of being alive.