The book tells the story of Lale Sokolov, a Slovakian Jew who was sent to Auschwitz-Birkenau in 1942. Lale was tattooed with the number 326 on his arm, which became a significant part of his identity. While working in the camp's administration office, Lale met a young woman named Gita, who had been transported to the camp from Slovakia. Despite the harsh conditions and the danger of being discovered, Lale and Gita formed a deep connection, which eventually turned into a romantic relationship.