Maugham acts as both the narrator and a fictionalized version of the real author. He is a worldly and observant writer who travels frequently across continents. He studies human nature without judgment, collecting stories from the people he encounters while maintaining an impartial, objective distance from their personal conflicts.

Larry is a young air corps pilot who returns home permanently changed by his military experiences. He is thin and wiry, possessing a quiet and magnetic nature. Instead of taking a traditional corporate job, he desires time to read and think. A profound need to understand the existence of evil drives his pursuit of truth.

Isabel is a tall and strong-willed young woman from a wealthy Chicago family. She is deeply attracted to her fiancé but possesses a highly pragmatic view of the world. She values social status, luxury, and the conventional ideal of hard work. Her ambitions directly conflict with the spiritual focus of the man she wishes to marry.

Elliott is a wealthy and elegant American expatriate nearing his fifties who lives primarily in Paris. He devotes his life to European high society, cultivating connections with titled and influential figures. Despite his superficial values, he is remarkably generous and a dedicated supporter of the Catholic Church.

Sophie is a young woman who grew up in the same social circle as Larry and Isabel. Initially appearing quiet and plain, she has an underlying intellectual curiosity, reads widely, and writes poetry. Her intense capacity for feeling leaves her highly vulnerable to emotional pain following a personal tragedy.

Gray is the broad-shouldered son of a wealthy Chicago stockbroker. He derives his sense of identity from his work and financial success. He embodies the conventional American ideals of hard work, ambition, and corporate responsibility that Isabel admires.

Suzanne is a French woman with a practical approach to survival and independence. She works as an artist's model and domestic companion for various painters in Paris. She possesses innate shrewdness, exchanging her labor and companionship for financial support while maintaining her autonomy.

Louisa is Isabel's mother and Elliott's sister. She is a socially conscious woman who worries deeply about her daughter's engagement to a young man without a conventional career path or sufficient income.

Henry is Gray's father and a highly successful Chicago stockbroker. He represents the wealthy corporate establishment and attempts to offer a respectable position in his firm to his son's rival.

Patsy is an older airman in the military who takes a young recruit under his wing. His combat experiences and subsequent fate serve as a major catalyst for a shifting worldview in the protagonist.

Kosti is a Polish miner who drinks heavily and works manual labor in France. Despite his rough exterior, he possesses a deep interest in mysticism and introduces new spiritual concepts to his roommate.

Herr Becker is a German farmer who provides manual labor work and shelter for two young men during their hiking trip across Europe.

Frau Becker is a farmer's wife who manages the household. She develops an attraction to a young farmhand and maintains a hostile rivalry with her daughter-in-law under the same roof.

Ellie is a widowed young woman living on a German farm. She despises her mother-in-law and actively seeks the attention of a young laborer working on the property.

Father Ensheim is a Benedictine monk who suggests that immersing oneself in the Church's daily rituals might lead to genuine belief and spiritual understanding.

Odette is a young French girl who receives a convent school education while her mother works to secure their financial future in Paris.

Monsieur Achille is a wealthy manufacturer with an interest in art. He provides an apartment and a stable income to his domestic companion.

Princess Novamali is a prominent member of the European social elite. Her exclusive parties represent the pinnacle of the society that certain expatriates value above all else.