A veteran history teacher in London whose career is abruptly ending due to a scandal involving his wife. In response to his impending dismissal, he abandons his standard curriculum to tell his students the sweeping history of his family in the Fens of East Anglia. He is philosophical and heavily reliant on storytelling to make sense of his turbulent reality.

Tom's older brother is a physically powerful but mentally challenged young man who lives a solitary existence in the Fens. Described by Tom as a "potato-head," Dick exhibits a childlike curiosity about the world, particularly concerning love. He relies heavily on raw instinct rather than intellect.

Tom and Dick's father is a hardworking and pragmatic lock-keeper on the River Leem. Following the early death of his beloved wife Helen, he becomes highly superstitious. He relies on folklore to survive his grief and struggles to communicate his deeper emotions to his sons.

Tom's wife triggers the present-day crisis by stealing a baby from a supermarket. In her youth, she is an adventurous and devout Catholic girl who captures the attention of the local boys. As an adult, her unfulfilled desire for motherhood drives her to extreme, delusional actions.

Tom and Dick's mother brings striking beauty and a nurturing spirit to the Crick household. She dies of the flu when Tom is nine, leaving a massive void in her family. Her history ties the humble Cricks to the prominent Atkinson brewing dynasty.

Tom's grandfather is a rebellious politician and the head of the New Atkinson Brewery. He is a somber, ambitious man deeply fearful of the future. His profound love for his daughter Helen drives many of his unorthodox life choices.

A childhood peer of Tom and Dick known for his crude bravado. His death in the sluice is initially ruled an accident, but the mysterious circumstances surrounding his drowning serve as the catalyst for Tom's lifelong obsession with uncovering the truth of the past.

An unruly high school student in Tom's history class. He is rebellious, terrified of the threat of nuclear war, and initially dismissive of history's value. He eventually becomes the primary audience for Tom's deeply personal tangents.

The headmaster of the London high school where Tom teaches. Once an idealistic educator who viewed the school as a ship bound for the Promised Land, Lewis has devolved into an apathetic figurehead focused more on public relations than the well-being of his staff.

Freddie's father is an opportunistic local man known around the Fens as a drunk. His poor parenting and illicit exploits are well known in the community.

A local woman living on the Fens who is rumored to be a witch. She possesses knowledge of folk remedies and operates in secret, acting as a grim, pragmatic figure when the local youth find themselves in desperate trouble.

The skipper of the Rosa II, a dredger operating on the vast Ouse River. He is a working-class Fenman who inadvertently becomes involved in the Crick family's search during a moment of crisis.