The novel serves as a prequel, tracing the childhood and young adulthood of the figure who will become one of fiction's most notorious killers. A brief prologue introduces Hannibal Lecter's "memory palace," a vast mental architecture where he stores knowledge and memories. The spaces devoted to his earliest years are incomplete, and certain places on the palace grounds contain screaming that Hannibal himself cannot visit.
In 1941, eight-year-old Hannibal lives at Lecter Castle in Lithuania with his parents and his nearly three-year-old sister, Mischa. When German bombers strike nearby on the second day of Operation Barbarossa, Hitler's invasion of Eastern Europe, Count Lecter, Hannibal's father, evacuates the family to a hunting lodge deep in the forest. They are accompanied by Mr. Jakov, Hannibal's tutor, a Jewish scholar expelled from the University of Leipzig. Before departing, Hannibal's mother entrusts valuables to Cook, the household cook, who hides them in a secret chamber behind the wine cellar.
While the family travels, Vladis Grutas, a Lithuanian Hiwi (a local volunteer collaborating with the Nazis), infiltrates the castle and watches Cook conceal the valuables. When German Totenkopf (Death's Head) SS troops arrive, Grutas proves his loyalty by identifying Cook as Jewish and executing him. The SS unit moves east with Grutas and the other Hiwis. Berndt, the family's hostler, escapes to the lodge.
A flashback reveals Hannibal's precocious intellect: He could read by age two. Mr. Jakov recognized his gifts and taught him to build a memory palace. The family survived three and a half years at the lodge on stored provisions and foraged food while Mr. Jakov taught daily lessons.
As the Eastern Front collapses in winter 1944–45, Grutas and his band desert their Nazi masters and loot the countryside, posing as medics in a Red Cross ambulance. Meanwhile, a Soviet tank arrives at the lodge seeking water. A German Stuka dive bomber attacks during the encounter, killing Hannibal's parents, Mr. Jakov, and the remaining household staff. Hannibal tries to save his mother, heaping snow on her burning clothes, but she is dead. He shields Mischa and carries her inside.
That night, Grutas and his five accomplices, Milko, Dortlich, Grentz, Kolnas, and Pot Watcher (Kazys Porvik), burst into the lodge. Grutas threatens to shoot Mischa if Hannibal resists. They chain the children to the banister. Kolnas steals Mischa's baby bracelet. Snowed in and starving, the men consume a deer, then turn to unspecified meat. Mischa grows feverish. In Hannibal's last conscious memory, the men come for Mischa. He fights desperately, but Grutas slams the barn door on his arm, breaking it, and beats him unconscious. Mischa calls "Anniba!" as she is carried away. Russian soldiers later find Hannibal mute, a chain locked around his neck.
By 1946, 13-year-old Hannibal lives in the castle, now a Soviet orphanage, still mute and prone to violent outbursts. His uncle, Count Robert Lecter, a painter, brings him to his chateau in France. There Hannibal first sees Lady Murasaki, the count's Japanese wife and daughter of the former Japanese ambassador to France. Her silhouette in a high window becomes a foundational image for him. Lady Murasaki takes Hannibal under her care, introducing him to ikebana (flower arranging), calligraphy, and Japanese aesthetics. She shows him an ancestral altar in the attic where samurai armor associated with the commander Date Masamune stands alongside photographs of Hannibal's parents. She invites him onto "the bridge of dreams."
At the village market, Paul Momund, a butcher and former Vichy collaborator, makes obscene remarks about Lady Murasaki. His blood-and-feather-smeared face triggers Hannibal's association with Grutas. Hannibal attacks Paul and speaks his first word: "Beast." The village commandant gives Hannibal one warning before arrest. When Robert confronts Paul at the next market, the count collapses from a heart attack and dies. Consumed by grief, Hannibal later finds Paul fishing and, when Paul attacks him, kills and beheads Paul with a samurai sword hidden in a lute case. Lady Murasaki discovers the head on the ancestral altar and stages the death as a Resistance reprisal.
Inspector Popil, a war crimes specialist from Paris, investigates and focuses on Hannibal. Hannibal passes a polygraph with no physiological reactions, attributed to either trauma or "a monstrous amount of self-control." Popil recognizes something in Hannibal he identifies as "Other," a quality he has never encountered. Hannibal and Lady Murasaki move to Paris, where Hannibal excels at the Lycée. He discovers paintings stolen from Lecter Castle being sold through dealers connected to Grutas, who murders one dealer aboard his canal boat, the Christabel, to prevent exposure.
Now 18 and the youngest person admitted to medical school in France, Hannibal works under Professor Dumas creating anatomical illustrations. In his garret, he draws the faces from his dreams on the walls, though he does not yet know their names. After witnessing Popil use hypnotic drugs on a prisoner, Hannibal secures a sample and injects himself. The drug breaks through his amnesia: He relives Mischa being taken and remembers the men burning their dog tags and papers before fleeing. He realizes the tags may survive in the lodge ruins.
Hannibal travels to Lithuania and excavates the lodge, finding Mischa's remains and six dog tags bearing the looters' names. He buries Mischa on a slope above the lodge. Dortlich, now a Lithuanian police officer, approaches but is ambushed. Under interrogation, Dortlich reveals that Grentz fled to Canada and Kolnas runs a café near Fontainebleau as Grutas' intermediary. Hannibal kills Dortlich.
Grutas, now operating as a businessman trafficking in women and stolen goods, sends Milko to kill Hannibal in Paris. Returning to France, Hannibal visits Kolnas' Café de L'Este and discovers Mischa's bracelet on Kolnas' daughter. Lady Murasaki pleads with Hannibal to surrender the criminals to Popil, offering him a life together in Japan. He replies, "I already promised Mischa," and leaves.
When Milko infiltrates the anatomy laboratory, Hannibal ambushes and kills him, learning Grutas' location. Hannibal smuggles an incendiary device into Grutas' fortified home and infiltrates during a cocktail party. He confronts Grutas but is seized by guards, including Mueller. As they prepare to cut Hannibal's throat, the bomb detonates. In the chaos, Hannibal shoots Mueller and escapes.
Grutas retaliates by kidnapping Lady Murasaki and telephoning an ultimatum: Bring all evidence at sunrise, or she dies. Hannibal recognizes the sound of ortolans, small caged songbirds kept at Kolnas' café, in the background. At the café, he bluffs Kolnas into revealing Grutas' location on the Christabel, then kills Kolnas and releases the caged ortolans into the night.
Racing south, Hannibal boards the canal boat at a lock and fights his way to Grutas, who shoots him in the back. Lady Murasaki, bound to a chair, distracts Grutas, and Hannibal slashes his Achilles tendons. Grutas makes a devastating claim: Pot Watcher fed Mischa to Hannibal in broth, and Hannibal unknowingly consumed his own sister. Hannibal screams denial and carves the letter "M" into Grutas' body. Lady Murasaki kills the boat captain to save Hannibal and urges him to stop. He tells her he loves her. She holds his bloody hands away: "What is left in you to love?" She dives into the canal.
Hannibal rigs the boat's Panzerfaust anti-tank weapons and walks away as the Christabel explodes, destroying all evidence. Popil arrests Hannibal but struggles to build a case. He confides that "the little boy Hannibal died in 1945 out there in the snow trying to save his sister. His heart died with Mischa." Lady Murasaki visits and senses something fundamental has changed: "Now there is only ice."
Over Popil's objections, Hannibal is freed and offered an internship at Johns Hopkins Medical Center in Baltimore. He returns to find Lady Murasaki gone. Her letter reads: "Goodbye, Hannibal. I have gone home." He dines alone and is not lonely. The narrative states he has entered "his heart's long winter. He slept soundly, and was not visited in dreams as humans are."
In a brief coda, Hannibal travels to Quebec and kills the last surviving member of the group, Bronys Grentz, at his taxidermy shop. On the train back, he reflects that killing Grentz was "preferable to skiing" (322). The novel closes with Hannibal riding southward, the blood-red claret shivering in his glass, a figure emotionally sealed and heading into his future.