Set in Chicago during the brutal winter of 2011, the story follows the Pearl family: Dashel (Dash), a Library Page at the Harold Washington public library; his wife, Summer (Sum); and their two children, 11-year-old Early and four-year-old Jubilation (Jubie). The Pearls live in a one-room apartment in Woodlawn, a South Side neighborhood. Despite their modest circumstances, the family is tightly bonded by a shared love of language, keeping a Quote Book, Word Book, and Onomatopoeia List. Dash, who was adopted as an infant and grew up in foster homes, has instilled in his children a reverence for words. His favorite poet, Langston Hughes, is a constant presence in their lives. The family's greatest shared dream is to one day own a house.
On a freezing January afternoon, Dash vanishes. A 911 call reports a bicyclist hit by an unmarked delivery truck, but when police arrive, they find only Dash's crushed bicycle, scattered groceries, and a pocket notebook filled with observations about repeating-digit times. There are no witnesses, no blood, and no footprints on the packed ice.
Sum calls the police repeatedly, but detectives treat the disappearance as routine. The family's bank account holds only $110. When their food and money run out, Early breaks a promise to Dash and tells Sum about a thick envelope of cash she once saw him hide inside an encyclopedia. Sum is shocked by the amount but relieved to have something to live on.
Sum visits the library seeking answers. Mr. Pincer, a supervisor brought in to handle budget cuts, questions her aggressively about a side book business. For about a month before his disappearance, Dash had been receiving boxes of old books from a supposed international bookseller named Lyman Scrub, cataloging them, and handing them off to a coworker named Al for delivery to a warehouse. Dash received cash for this work. During the meeting, Jubie blurts out that the family found hidden money, deepening suspicion.
That same night, three men and a woman wearing silver masks break into the Pearl apartment. They demand to know where Dash kept something, using the word "ice," slang for diamonds that the Pearls do not yet understand. One intruder grabs Early and threatens her; Sum is pushed and hits her head. They take all the family's books, notebooks, cash, and Sum's wallet. Only one book survives:
The First Book of Rhythms by Langston Hughes, a treasured first printing that slipped beneath broken furniture. A neighbor urges Sum to take the children to a shelter immediately.
At a police station, Sum learns there is a warrant for Dash's arrest and the FBI is involved. Mr. Pincer told detectives that no one named Al worked on the sixth floor, Dash's department, and that the bookseller Lyman Scrub does not exist. A detective shows Sum a tiny diamond found in their wrecked apartment, identified as a stolen gem from the 2003 Antwerp Diamond Center heist, the largest diamond theft in history. Thieves stole gems worth an estimated 100 to 140 million dollars, and most were never recovered. Sum insists the stone was planted and Dash is innocent, but she recognizes their poverty makes them less credible.
The Pearls are taken to Helping Hand, a family shelter on the North Side. Mrs. Happadee, the shelter director, assigns them a bunk-bed cluster in a large open dormitory. Early befriends Velma, a warm older woman working to regain custody of her own children, and meets Darren, a boy her age, and Aisha, a 10-year-old fellow shelter resident. At the nearby Hughes School, Early is mocked as a "shelter kid." Sum sinks into depression, unable to find work or legal help. Conditions worsen when Darren's family vanishes overnight and Aisha is hospitalized with pneumonia. Jubie develops a persistent cough, and Sum sometimes cannot get out of bed.
Early draws strength from Hughes's poetry, formulating her own equation: Roots plus Wings plus Dreams equals Home. She begins hearing Dash's voice urging her to hold fast to dreams and to "research rhythms." She resolves to investigate his disappearance.
Remembering a teacher Dash once mentioned, Early tracks down Mr. Skip Waive through a school office worker. Mr. Waive, a retired teacher who is limping and visibly unwell, listens to her story, declares Dash must have been coerced, and agrees to investigate at the library. He later reveals he, too, is living in shelters.
After an outburst at school in which Early reveals her family's homelessness, Sum decides to homeschool Early so the three Pearls can visit the library together daily. Early charms her way into Mr. Pincer's office, claiming she wants to collect memories of her father, and fabricates a story about the diamond to deflect suspicion. She notices that Mr. Pincer's assistant, Ms. Mary Whissel, speaks with an accent identical to one of the masked intruders.
A coworker named Mr. Alslip privately confirms he is the person Dash called "Al." He reveals that when Dash kept
The First Book of Rhythms and gave Al money to pay for it, Al never delivered the payment out of fear. When criminals asked who had handled that box, Al gave them Dash's name. He also tried to communicate the warehouse address to Dash through coded number patterns but failed before Dash disappeared.
Events accelerate. Mr. Pincer bans Mr. Waive from the library. Through a vent, Early overhears Mr. Pincer, Mr. Alslip, and Ms. Whissel discussing someone who has been "finally seen" and "could be gone." She interprets this as evidence that Dash has escaped and rushes her family from the building.
Back at the shelter, Mr. Alslip attempts to steal the Pearls' belongings, but Velma catches him. Mrs. Happadee moves the family to a private room with a locking door. Early finds a razor-blade cut at the spine of
The First Book of Rhythms and discovers a tiny diamond in the bag Al had been filling. She hides the stone. Police share major developments: Mr. Alslip has confessed, Mr. Pincer is arrested as a fraud who forged his library credentials, and Ms. Whissel is revealed as a member of the crime ring. Dash is confirmed innocent.
Early realizes the warehouse address is 369, derived from Dash's repeating-digit times: 1+1+1 equals 3, 2+2+2 equals 6, 3+3+3 equals 9. She gives the diamond and the address to Velma, who brings them to the police. The FBI raids the warehouse in Marquette Park, arrests armed guards, and finds the room where Dash was held prisoner. The criminals confirm he escaped.
Meanwhile, Early channels her experience into a project called Home Dreams, organizing shelter kids across Chicago to photograph abandoned buildings and write descriptions imagining themselves living there. The children's letters and photos are mailed to the mayor, foundations, and the president.
In the final chapter, a bone-thin man with wild hair walks into Helping Hand. When the door to the Pearls' private room opens, the family holds one another. Dash explains that his kidnappers demanded
The First Book of Rhythms because its unusually heavy spine contained smuggled diamonds. To protect his family, he told them he had left the book on a train. After weeks of captivity and beatings, he escaped by squeezing through icy window bars. A kind restaurant owner sheltered him, and Dash spent weeks searching shelters for his family, afraid to contact police because his kidnappers warned he would be arrested. He learned his name was cleared only that morning from a newspaper.
An FBI agent returns the book and reports that seven more diamonds were removed from its spine, nine total, fitting the rolling pattern of threes. The family may receive reward money. The Chicago Public Library offers Dash a full-time position. Dash proposes naming their future home "Hold Fast." The novel closes with the family together in their shelter room, holding fast to dreams.