Mitchell is an anxious, ordinary-looking young man from Kansas City who works as a junior associate at the financial firm Fitzsimmons Sherman in New York City. Driven by a deep fear of the unknown, he uses his intelligence to calculate the probabilities and financial costs of disasters. This obsession alienates him socially but makes him uniquely suited for a career in risk analysis.

Jane is a recent Princeton graduate with a degree in philosophy who joins FutureWorld as a forecaster. Self-conscious about her academic background, she often adopts coarse language to prove her toughness in the corporate world. Under Mitchell's instruction, she learns to pitch disaster scenarios to clients, though she remains skeptical that the catastrophes they sell will actually occur.

Alec is the eccentric, energetic founder of FutureWorld, a consulting firm operating out of the Empire State Building. He recognizes Mitchell's talent for identifying worst-case scenarios and recruits him with promises of high salaries and sign-on bonuses. He views corporate anxiety as a highly profitable market and aggressively expands his business by exploiting loopholes in disaster insurance claims.

Ned is the egocentric general partner of his family's firm, Nybuster, Nybuster, and Greene. Shielded by extreme wealth and status, he initially dismisses warnings about geopolitical or environmental catastrophes. He becomes highly engaged only when disaster predictions directly threaten his personal assets or family members.

Elsa is a former college classmate of Mitchell who lives with Brugada syndrome, a condition that means her heart could stop without warning. She resides at Camp Ticonderoga, a homesteading commune in Maine, where she gardens and canoes. Her choice to live far from medical facilities confounds Mitchell, prompting a regular exchange of letters between them.

Sandy is the chairman of Fitzsimmons Sherman. He asks his employees to calculate the monetary value of their own lives for the firm's disaster planning. He treats his lower-level employees with condescension and dismisses Mitchell's desire to transfer into the Risk department.

Tibor is Mitchell's Hungarian American father who lives in Kansas City. He operates a block of rundown, foul-smelling apartments known locally as the Zukorminiums. He strongly believes in the American capitalist system and is highly enthusiastic about the high salary Mitchell earns at FutureWorld.

Rikki is Mitchell's mother in Kansas City. She frequently worries about her son's isolated lifestyle in New York City and encourages him to go out and enjoy his youth rather than staying trapped in his apartment.

Mary is the secretary at FutureWorld. She insists that everyone in the office refer to her formally by her surname. She manages the phone lines and schedules appointments for the rapidly growing company.

Hank is a physically large, decisive man who takes charge during emergency situations. He intends to travel to the Flatlands on the far edge of the city to establish a homestead, actively recruiting others to join his efforts.

Billy is Elsa's boyfriend who lives with her at the homesteading community in Maine. He works on the farm and participates in the commune's daily agricultural activities.