In World War II Italy, a French-Canadian nurse named Hana is transferred to an Italian monastery, where she tends to a dying man suffering from critical burns. Though he has forgotten his name, the man, who speaks English, possesses The Histories of Herodotus, a bound book in which he has kept notes and mementos throughout his life. Another patient, a Canadian intelligence officer named David Caravaggio, arrives at the monastery and begins to talk with the English-speaking man, who slowly reveals his past to Caravaggio, Hana, and Kip, a Sikh soldier for the British Army, there to locate and defuse unexploded bombs. The patient recalls that he was sent on an expedition to the Sahara Desert in the late 1930s. In his recollections, he is revealed to be Count László de Almásy, a Hungarian cartographer working for the Royal Geographical Society: While traveling through Egypt and Libya with his British friend, Peter Madox, Almásy meets and falls in love with Katharine Clifton, a married Englishwoman whose husband, Geoffrey, lends his airplane to Almásy’s mapping expedition. The group locates an ancient collection of cave paintings known as the Cave of Swimmers. Katharine paints the site, and gives two of her watercolor renditions to Almásy, who pastes them into his Herodotus book. In Cairo, Egypt, Katharine and Almásy begin a love affair. To preserve her marriage, Katharine soon ends it. Back in the present, Hana and Kip get to know each other and fall in love. When Kip is called to another post, the new lovers promise to meet again. Almásy remembers that Geoffrey Clifton attempted to kill himself and Almásy by purposely crashing his airplane: Geoffrey misses Almásy on the ground, but kills himself and injures Katharine, his passenger. Almásy takes her to the Cave of Swimmers to safely recuperate. Along the way, he notices a silver thimble that he gave her as a present, which she is wearing as a necklace. She confesses her continued love for Almásy. He leaves her in the cave and begins a days-long trek through the desert in search of help. He is briefly detained by British soldiers, who suspect him of being a German spy, but escapes to the Kufra Oasis, where Peter Madox has left his Tiger Moth biplane. Almásy flies the Tiger Moth back to the Cave of Swimmers, where he finds Katharine dead. Grief-stricken, he loads her body onto the plane. As he attempts to fly to safety, the Tiger Moth is shot down by the German army. Almásy is saved by Bedouins, and ultimately transferred to Italy, where he came to be under Hana’s care. Having told his full story, Almásy convinces Hana to give him a lethal dose of morphine. She obeys his wishes, and as he dies, the nurse reads aloud from a page she found tucked in his Herodotus book. It is a love letter from Katharine, written during her final days in the Cave of Swimmers. As Hana and Caravaggio finally leave the monastery, she takes Almásy’s book with her.