The following version of this book was used to create this study guide: Ng, Celeste. Our Missing Hearts. Penguin Press, 2022. Kindle Edition.

Bird Gardner is a 12-year-old boy who lives in a futuristic version of Cambridge, Massachusetts with his father, who was once a linguistics professor but now works shelving books in a university library. Bird’s mother, Margaret Miu, is a Chinese American poet who disappeared when Bird was nine. Since she left, others have begun calling Bird by his official name, Noah. Bird and his father have moved from a house in the suburbs to a small apartment.

Bird has always accepted the society he lives in. In school, he learns about the Preserving American Culture and Traditions Act (PACT), which teaches that China is a dangerous enemy of the United States. The government has enacted a range of oppressive measures under PACT, including removing books from libraries and even removing children from their families if their parents are deemed “unloyal” in any way. Bird’s friend Sadie questioned PACT and the government’s teachings, but ever since she ran away Bird spends much of his time alone. Bird learned from Sadie that a line from his mother’s poem – “Our Missing Hearts” – has been used as a slogan by anti-PACT protestors.

One day, Bird receives a letter from his mother containing a drawing of cats, which he believes is a reference to a story she once read to him. He searches for information about the book and his mother on the school computers, but finds nothing. The local public librarian tells him the title of the book - The Boy Who Drew Cats - but it has been removed from the library by patrons who claimed that it was pro-PAO (Person of Asian Origin). Bird’s father catches him sneaking into the university library to look for the book and warns him not to draw attention to their family. As Bird is walking with his father, a man shoves Bird and calls him a racist slur. Bird also witnesses a white man verbally attack a Cantonese man at a pizza restaurant.

Bird realizes that The Boy Who Drew Cats is a clue that leads him to the bedroom closet in his old family home. There, he finds a letter from his mother with the word “Duchess” and an address in New York City. After getting advice from the public librarian, Bird travels to New York City and meets with the Duchess in an opulent home. The Duchess then directs him to an abandoned townhouse, where he finds his mother, who is working on a secret project that involves constructing wires.

Bird’s mother tells him about the economic and political crisis that sparked the PACT and increased government control. She weathered this crisis with her strong-willed and independent friend Domi, then met Bird’s father, Ethan. During the Crisis, Margaret's father was murdered in a racist attack and her mother died shortly afterward. Following this trauma, Margaret and Ethan moved to the suburbs, had Bird, and attempted to live peacefully. Margaret published a book of poetry. The line “Our Missing Hearts” from the book is written on a poster by an anti-PACT protestor named Marie, who is killed by police. Margaret's book receives more attention; she is targeted by racist PACT supporters and eventually forced into hiding.

Margaret visited Marie’s parents, who told her stories about Marie. She became involved in a network of PACT protestors who visit families that had their children taken away from them or “removed” by the government due to their supposedly subversive ideologies. She met with her old friend Domi, who has now inherited her father's fortune and is in fact the Duchess. Domi makes large donations to libraries and supports Margaret in her political resistance efforts, allowing her to stay in an old brownstone while she plans a protest. Bird accompanies his mother as she plants bottle caps around the city in preparation for her plan.

Domi drives Bird and Sadie to a safe cabin in the woods outside the city while Margaret carries out her plan. The two children enjoy experiencing nature and solitude, but become worried as a day passes and Domi does not return. Meanwhile, Margaret has connected the system of bottle caps to an electronic speaker that allows her voice to boom out across the entire city. She reads out details and stories about the children who have been taken from their parents by the government. She refuses to stop reading until the authorities track her down.

Domi and Bird’s father arrive at the cabin. Although Margaret is now missing, the group is committed to continuing to search for the missing children, and to share their stories and Margaret’s poetry.