Todd is a 54-year-old lawyer living in Cambridge, Maryland. Afflicted with a chronically weak heart, clubbed fingers, and an infected prostate, he navigates life with the constant awareness that he could die at any moment. He approaches his legal career and personal relationships with analytical detachment, adopting various philosophical personas to cope with his mortality before settling on extreme cynicism. He spends the primary timeline of the story meticulously planning his own suicide.

Harrison is Todd's wealthy, athletic best friend and the heir to a successful pickle company. He begins his adult life as a passionate Marxist organizing labor movements but eventually becomes disillusioned, settling into an administrative role at his father's company. He tends to absorb the opinions and moods of the people around him, making him highly impressionable.

Jane is Harrison's athletic and beautiful wife. She shares her husband's willingness to question societal rules, leading her to initiate a long-term affair with Todd with Harrison's full knowledge and encouragement. She lives a life of privilege and comfort, displaying an independent and increasingly unpredictable spirit that sometimes unsettles the men in her life.

Captain Osborn is an 83-year-old retired oyster dredger residing at the Dorset Hotel. Crippled by severe arthritis, he is vocally miserable about his failing body and frequently complains about the physical indignities of old age. Despite his cantankerous nature, he provides Todd with a reliable source of blunt, unpretentious company.

Mister Haecker is a 79-year-old retired high school principal who lives alone at the Dorset Hotel. Having no surviving family, he attempts to maintain a stoic and optimistic attitude about his twilight years, frequently quoting classical literature to justify his stance. His formal demeanor masks a deep anxiety about death and isolation.

Todd's father was a lawyer who valued neatness and precision above all else, idealizing nineteenth-century surgeons who worked without dirtying their clothes. Plagued by debt from poor investments, he hanged himself in his cellar in 1930, an event that deeply scarred Todd and fundamentally altered his worldview.

Jeannine is the three-and-a-half-year-old daughter of Harrison and Jane Mack. Born during a brief period of estrangement between the Macks and Todd, her physical features do not strongly resemble either man, leaving her exact parentage a quiet mystery. She is highly inquisitive, constantly asking Todd questions about her surroundings.

Betty June is a woman from Todd's past who initially pines for an older man before engaging in a brief, unfulfilling intimacy with a teenage Todd. Following a traumatic separation, she becomes a sex worker in Cambridge and Baltimore, harboring deep resentment toward Todd for mocking their intimate encounter.

Dr. Rose is a local physician in Cambridge and one of the few people aware of Todd's precarious health conditions. He frequently urges Todd to undergo surgery for his infected prostate and to take better care of his heart, though Todd typically ignores his advice.

Jacob R. Adam is the charismatic owner and captain of Adam's Original and Unparalleled Floating Opera. He is a natural showman who operates a theatrical riverboat powered by a volatile combination of electricity and acetylene gas. During performances, he adopts entirely different, florid personas to entertain the crowds.

Colonel Morton is the wealthiest man in town, fiercely proud of his independence and resentful of owing anyone a favor. He becomes embroiled in a petty lawsuit against a local Democrat after feeling snubbed during a presidential visit to Cambridge.

William T. Butler is a Democratic investment broker in Cambridge. He draws the ire of Colonel Morton after securing an exclusive invitation to board President Franklin D. Roosevelt's ship during a local political event.

Mrs. Morton is Colonel Morton's significantly younger second wife. She participates eagerly in the extravagant, chaotic atmosphere of her husband's parties, eventually engaging in a brief, drunken encounter with Todd.

Smitty is a young man in his late twenties who completely ignores Betty June's affections. He secretly marries another woman, devastating Betty, and is later killed in combat during World War I.

Jimmy is Todd's legal partner at the firm Andrews, Bishop, and Andrews. Todd relies on him to finalize pending legal matters, leaving him detailed instructions on how to secure Harrison's inheritance.

Bill Froebel is the capable and highly motivated lawyer hired by Mrs. Mack. He relies on impassioned, poetic courtroom speeches to sway judges and uncovers damaging evidence regarding Harrison's past political donations.

Mrs. Mack is Harrison's mother and the widow of Harrison Sr. She battles her son for control of the family's immense wealth, complicating the lawsuit by casually using her late husband's preserved feces as fertilizer for her garden.

Harrison Sr. was an incredibly wealthy businessman whose declining mental health in his later years led to highly erratic behavior. He constantly rewrote his wills to punish or reward his family members and famously demanded that all of his bodily waste be preserved.

Jerry is the manager of the Dorset Hotel in Cambridge. He maintains a friendly, flexible relationship with Todd, willingly holding onto messages and looking the other way when Jane Mack visits Todd's room against standard hotel policy.

Mrs. Aaron is the housekeeper employed by Todd's father during Todd's youth. She contributes to a critical environment in the household, leaving a young Todd wishing for solitude so he can work on his hobbies without judgment.