In the summer of 1906, wealthy playboy Harry K. Thaw murders famed architect Stanford White in cold blood in New York city, ostensibly out of a jealous rage over an affair White had with Thaw’s wife, Evelyn Nesbit, before she was married. Around the same time, Mameh, Tateh, and Little Girl immigrate from an Eastern European country to the United States, where they start trying to make a new lives for themselves in the New York city tenements.
Meanwhile, one sweltering summer day, fate brings Harry Houdini (one of Little Boy’s heroes) to Little Boy’s front door. It’s a big summer for Little Boy’s family—Father is preparing to set out on one of Robert Peary’s north pole expeditions.
One day, while awaiting her husband’s trial, Evelyn decides on a whim to visit the Lower East Side. There she encounters Tateh and Little Girl on a street corner (Tateh, having discovered that Mameh’s employer was sexually assaulting her, has cast her out for her allegedly loose morals). Evelyn becomes obsessed with Little Girl and insinuates herself into the family’s life. But when Tateh brings Evelyn along to a lecture by famed political activist Emma Goldman, Goldman recognizes—and outs—Evelyn. Tateh flees in horror. Mother’s Younger Brother (who is obsessed with Evelyn and has been following her around the city all summer) trails Evelyn and Goldman back to Goldman’s rooming house, where he listens as Goldman lectures Evelyn about class justice, and women’s liberation. Subsequently, Younger Brother and Evelyn become lovers.
With Father away, Mother takes increasing responsibility for the household and for the family’s fireworks and patriotic wares company. As she does so, she realizes it’s far easier than she expected. One day as fall approaches, she discovers an abandoned baby hidden in her garden. She decides to shelter and care for the baby and its mother, Sarah, a poor Black washerwoman.
By the time Father returns home the following spring, Thaw’s trial has concluded, he and Evelyn have divorced, Evelyn has left Younger Brother for a ragtime dancer, Little Boy has started school, and Mother has begun to dabble in women’s liberation literature. Soon after Father’s return, Coalhouse Walker Jr., a professional musician originally from St. Louis and the father of Sarah’s baby, comes to court Sarah. Because he is Black but not sufficiently deferential (he dresses well, he drives a new Model T, he brims with self-confidence, and he speaks to the family as equals) he upsets some people—particularly local volunteer fire chief Willie Conklin, and, to a lesser extent, Father himself.
Eventually, Sarah agrees to marry Coalhouse. But soon afterward, Conklin and his men harass Coalhouse and destroy his car. Coalhouse tries to seek justice through legal means, but society and the authorities frustrate him at every turn. Coalhouse decides to postpone the wedding until the harms against him are rectified. He wants his now destroyed car returned in mint condition and for Conklin to apologize. Sarah, trying to support Coalhouse, tries to petition the Vice-President (in New York campaigning for the 1912 election) for help, but the Secret Service, misidentifying her as a potential assassin, forcibly stop her. Mishandled by the Secret Service and the local police, Sarah soon dies of her injuries.
Coalhouse Walker Jr., crazed by grief and rightfully offended by the racist and prejudicial treatment he has had to endure, begins a campaign of terrorist violence aimed at getting his demands met. First, he attacks the headquarters of the volunteer firefighters who harassed him, killing five men and setting the building ablaze. Soon afterward, Younger Brother (who, bereft over Evelyn’s abandonment, has become involved in Goldman’s anarchist revolutionary circle) seeks Coalhouse out in his Harlem hideout and joins Coalhouse’s band in their quest for justice. A capable designer of fireworks and other incendiary devices, Younger Brother starts making bombs, which the group uses in their second attack against another fire station.
Desperate to escape the chaos and violence, Father, Mother, Grandfather, Little Boy and Sarah’s baby go to spend the summer in Atlantic City, where they meet Tateh and Little Girl. After Tateh fled New York City, he did a brief stint as a textile mill worker in Massachusetts before abandoning factory work altogether and audaciously pursuing his art. This led to a contract for flipbooks from a novelty company, which Tateh parlayed into a successful career as a film producer. Now comfortably wealthy and established in American society, he calls himself the Baron Ashkenazy. Little Girl and Little Boy quickly become friends.
While the family is in Atlantic City, Coalhouse and his cohorts decide to take J. P. Morgan, one of the richest and most powerful men in the country, hostage in his Upper East Side mansion. But they’re foiled by their own ignorance—they accidentally storm Morgan’s private library, not his house, because the two buildings sit next to each other and the library looks fancier. Moreover, Morgan isn’t even home: he left the country on a quest to uncover esoteric and occult knowledge about human reincarnation in Egypt. Coalhouse, Younger Brother, and their compatriots take over the library, wire it with dynamite, and promise to blow it up unless the authorities return Coalhouse’s Model T in mint condition and turn Willie Conklin over to him for justice.
On learning of the crisis, Father rushes back to the city, where he becomes involved in the police response, coordinated by New York District Attorney Charles S. Whitman. Eventually, Father becomes the go-between who helps to negotiate terms between the authorities and Coalhouse. When Whitman finally capitulates and forces Willie Conklin to repair and rebuild Coalhouse’s Model T, the standoff ends. Coalhouse negotiates for the safe release of his compatriots, including Younger Brother. When Coalhouse himself finally leaves the library, the police waste no time in shooting him dead.
After Coalhouse’s death, Younger Brother takes the Model T and drifts across the country. Eventually, he ends up in Mexico where he joins the army of freedom fighter and insurrectionist Emiliano Zapata. He is killed in action. Mother grows increasingly disillusioned with Father as the years go by because of his old-fashioned views on race, gender, and American society. Eventually, they separate, although they don’t divorce. Father goes to work for the State Department and dies when a German U-Boat sinks the Lusitania at the outset of World War I. After a suitable period of mourning, Mother and Tateh marry and move their blended family to California where they live happily together.