Set in two timelines separated by roughly 1,200 years, this novel alternates between Han Yu, an 11-year-old boy in Tang dynasty China, and Luli Lee, an 11-year-old girl in Depression-era Chinatown, New York City. Their lives connect across centuries through a piece of silk, a shared love of steamed buns, and a determination to save the people they love most.
In 731 CE, Han Yu lives in Chang'An, the Tang dynasty capital. Animals have been drawn to him since birth, earning him the nickname "Tiger Boy" after his mother's encounter with a tiger near their home. His older brothers Bo and Ming and his younger sister Li all excel at their studies, but Han Yu has failed three apprenticeships and finds his only talent making steamed buns alongside his father, Baba, at the family's market stall. Li studies herbal remedies under their aunt Falong, an herbalist. Han Yu's closest companions are his dog Lok, three magpies, and a mistreated camel named Lotus. A deadly lung disease is spreading along the trade routes into the city.
In October 1931, Luli lives at 59 Mott Street, a five-story building housing her family's Jade Palace Restaurant, a gift shop run by honorary uncle Quong, and several apartments. The family has a mortgage on the building, and Luli dreams the restaurant will one day be hers. But business has collapsed: Customers have vanished, and her father disappears each morning without explanation. Luli and her best friend Sam, Quong's nephew, hope to turn the gift shop's back room, which holds old silk fragments bearing faint Chinese calligraphy, into a museum to attract visitors. A foreclosure notice arrives, meaning the bank will reclaim the building because the family has missed a payment.
In Chang'An, Li falls ill, Bo develops a cough, and the emperor orders sick families isolated in monastery hospitals. Honchiu, a retired merchant and the family's neighbor, offers Baba a lucrative job transporting goods to Tianshui, a trading city 650 li (roughly 200 miles) west. When officials take the family to a monastery hospital, Baba tells them he has only three children, deliberately omitting Han Yu to keep him free. Han Yu returns from an errand to find his house empty; neighbor Fenggan explains that Baba lied to protect him.
One of Honchiu's associates delivers the goods Baba was to transport, along with travel papers and tea bricks for trading. Realizing the family needs the income, Han Yu resolves to make the journey himself. He uses the tea bricks to buy Lotus from her abusive owner, freeing her. When the man pursues him shouting "Thief!" a market official intervenes. Han Yu steps outside Chang'An for the first time, setting out with Lok, Lotus, and the magpies.
In New York, Luli's mother takes a second job at a garment factory. Francie, Luli's best school friend, takes her beyond her parents' neighborhood boundaries, and on Broadway, Luli sees her father in a long unemployment line, revealing the depth of the family's crisis.
Han Yu's journey is grueling. Two merchants try to steal Lotus but flee when something unseen in the woods terrifies them. When his cart shatters against a rock, Han Yu despairs, but the next morning a cheerful young traveler named Du Fu arrives. A poet who has twice failed the imperial civil service examinations, Du Fu becomes Han Yu's close friend and traveling companion.
Luli, Sam, and neighbor Mr. Malone Sullivan renovate the gift shop's back room into a small museum. When Yiyi, the restaurant's head chef, moves into the family's apartment so his unit can be rented out, the cramped quarters create tension.
Han Yu and Du Fu arrive in Tianshui with one day to spare. Han Yu delivers the goods to the awaiting merchant, Wang Juyi, and uses a bonus payment to buy a small piece of silk for Li, who has always dreamed of touching silk. Wang Juyi reveals devastating news: Han Yu's entire family has the lung disease, and Li is especially sick. A con man named Rong tricks Han Yu and steals most of his coppers. Wang Juyi tells Han Yu the real Seven Star Grasses, a fabled healing remedy, are said to exist in Dunhuang, 1,300 li farther west across the Gobi Desert.
At the Metropolitan Museum of Art, a guide named Francisco shows Luli's class a handscroll painting of a boy traveling with two camels and a dog along what appears to be the Silk Roads. Luli feels a deep, unexplained connection. Francisco later visits the gift shop and, impressed by the silk fragments, offers to have a museum expert examine them. Walking through the pushcart-filled streets of Hester Street, Luli conceives her plan: She can make steamed buns and sell them from a pushcart.
Du Fu initially refuses to accompany Han Yu to Dunhuang but returns the next morning, unable to let him go alone. At Han Yu's request, Du Fu writes his poem "Morning Rain" on the silk, creating a treasured artifact. They cross the Qilian Mountains and enter the Gobi Desert, enduring weeks of bitter cold. A massive sandstorm engulfs them. Han Yu wraps the silk around Du Fu's face and throws his body over his friend as sand buries them both.
Yiyi refuses to teach Luli to cook, so she sneaks into the locked kitchen and teaches herself. When caught, Yiyi reveals the source of his fear: Years ago, his young son died from burns after his sleeve caught fire while checking steamed buns on the stove, and his wife returned to China in grief. Yiyi finally tells Luli her buns are good and begins teaching her. Luli stops attending school, redirecting her tuition toward the mortgage.
Han Yu awakens in a cave at the Thousand Buddha Caves near Dunhuang, rescued by a young monk named Bankei, who tells him a tiger led rescuers to where Han Yu and Du Fu lay buried. After Du Fu recovers, Han Yu journeys alone to Crescent Lake, where a mysterious woman cuts the Seven Star Grasses for him and instructs him to boil them into tea.
The gift shop is broken into, and the burglar strikes Quong with a metal bar, leaving him in a coma. Sam tends to his uncle while Luli and others maintain a vigil. Refusing to despair, Luli rallies Yiyi and launches the pushcart business, selling out 50 buns on her first day with Francie's help. On the sixth day, Quong wakes.
Han Yu, Du Fu, and Bankei journey home through brutal winter. After 178 days away, Han Yu returns to Chang'An, where Falong is caring for his gravely ill family. He and Falong boil the Seven Star Grasses into tea; within eight days, the entire family is recovering.
Francisco confirms that scientific analysis dates the silk to between 700 and 900 AD. While Sam reads aloud from a book of Chinese poetry, Luli recognizes Du Fu's poem "Morning Rain" as the text on the silk and calls Francisco, who confirms the connection. Art thief Oslo Goedertier overhears the discovery and later tries to force Luli and Sam into a car. Neighbors rush to their defense, and both Oslo and his accomplice are arrested. Detective Yates reveals Oslo also committed the robbery and assault on Quong.
The Metropolitan Museum offers to buy the silk. Luli negotiates the price from $2,000 to $6,000. Quong uses part of the proceeds to pay the remaining $1,200 on the Lees' mortgage, making them homeowners, and buys Yiyi a boat ticket to China to reunite with his wife. Luli returns to school, Sam enrolls for the first time, and the pushcart business thrives.
On the Dragon Boat Festival in Chang'An, the tiger appears briefly before vanishing, leaving the lost silk with Du Fu's poem hanging from the branches of Han Yu's pear tree. Du Fu arrives in the purple robes of a government official, having passed the imperial examinations. Han Yu promises to protect the silk and pass it down through generations. In New York, on the same festival day in 1932, Luli's class visits the museum's new exhibit, where the silk hangs beside the scroll painting of the boy with two camels and a dog. Luli notices for the first time a tiger painted behind the boy, hovering protectively, and feels a connection across a thousand years. Sam tells her he is hungry, and she links her arm in his. Fifty-nine Mott Street, dim sum, and home are waiting.