Marvelous is an 89-year-old woman living a solitary life in a caravan parked in a remote Cornish tidal creek. She spends her days swimming naked in the cold water and tending to the natural world, operating as an archetypal wise woman and healer who has delivered many of the local babies. Her long life has been marked by deep loves and profound losses, prompting her to lock away the boathouse where she once lived. Guided by dreams and local folklore, she prepares for a fated arrival that disrupts her quiet isolation.

Drake is a disillusioned World War II veteran returning to a bomb-scarred London with a letter he promised to deliver for a dying comrade. He suffers from persistent anxiety, tremors, and survivor's guilt, finding no comfort in the postwar world. Unable to cope with his haunting memories of the war and his childhood cousin Missy, he flees to Cornwall intending to end his life. Instead, he collapses in the woods and wakes under the unconventional care of an elderly healer.

Missy is Drake's childhood friend and third cousin who bonded with him over their shared status as orphans. During the war, she survived the bombing of the Café de Paris, an event she recounts with detached coldness. She works as an office clerk and a life model for an elderly painter, living in a small lodging with a caged linnet named Buddy. Despite her glamorous exterior, she carries intense shame regarding her actions during the Blitz and struggles with severe emotional dissociation.

Known as "Singer Jack" and later "Paper Jack," Jack is a former copper miner with a poetic spirit. He earned his early nickname by singing to brighten the dark days for his fellow underground workers. Unlike his pragmatic brother Jimmy, Jack is a dreamer who feels stifled by his circumstances and the hazards of the mines. His romance with Marvelous is derailed by tragedy, leading to a decades-long absence before he finally returns to her in declining health.

Peace is a 29-year-old baker who returns to her family's former home, a village that originally ostracized them. She is a practical, broad-shouldered woman who approaches her craft with intense dedication, believing that baking requires investing one's memories and emotions. Equipped with a jar of sourdough starter from her late mentor, she aims to breathe new life into the abandoned hamlet while carrying the quiet grief of her family's history.

Jimmy is a charismatic but deeply insecure Cornish copper miner. As Marvelous's second love, he views her as an indispensable charm to ward off misfortune underground. He is intensely protective of his reputation and status within the community, contrasting sharply with his introspective brother, Jack. His possessive nature and impulsive decisions complicate a growing love triangle.

Dr. Arnold is a kind, empathetic physician living in Cornwall. He lost his stepson Dougie in the war and receives Drake with understanding rather than suspicion. Early in his medical career, he treated a grief-stricken young woman living wild in the woods, giving him an unexpected historical connection to Marvelous Ways and her family's legacy.

Ned is a quiet, decent local fisherman who lives a somewhat lonely life on the Cornish coast. He is observant and thoughtful, expressing his growing affection for the new baker through gifts of fresh seafood and carefully written letters. He offers steady, undemanding masculine companionship to Drake, providing a calming presence on the open water.

William is Marvelous's father, a man who brought his wife from the American South to London before settling in the remote Cornish creek. Following his wife's tragic death, he lost his will to fully engage with the world, wandering the peninsula for years to learn ancient healing arts. He eventually raised his daughter in a traveling caravan, teaching her the ways of a healer.

Simeon is Peace Rundle's older brother and a World War I veteran. He returned from the trenches suffering from severe combat trauma. His subsequent suicide at home horrified the local villagers, who stigmatized his family and erased his name from the local war memorial.

Dougie is a fatally wounded British soldier who lost his arms above the elbow during the fighting in France. In his final moments, he speaks of his home in Cornwall and extracts a solemn promise from Drake to hand-deliver a letter to his father, Dr. Arnold.

Wilfred is Peace's former mentor, an experienced baker who taught her the emotional and physical requirements of their craft. Upon his death, he leaves her a paid lease on a bakehouse and his prized sourdough starter, ensuring his legacy continues through her work.