Night Comes Down is set in a remote town in the borderlands between England and Wales in the early years of Queen Victoria's reign.

Grace Matthews, the only child of the town's learned doctor, loves the woods, the valleys, and the streams in her quiet corner of the world. She is a loner and spends as much of her life as she can outdoors-her desire to be in nature only curbed by her father's unceasing wish to burden her with chores after the untimely death of her beloved mother.

Whenever she can get away, Grace watches in fascination and quiet horror as a branch line of the railway is built in the next valley over from hers. Before too long she finds the navvies' camp and, against all her instincts, falls in love with a farm boy called Sean from County Sligo in Ireland who has his own story to tell.

Meanwhile, Grace's father's habitual taking of snuff leads him towards an ever greater mental and physical breakdown.