"The 100-Year-Old Man Who Climbed Out the Window and Disappeared" is a novel by Swedish author Jonas Jonasson. It follows the adventures of Allan Karlsson, a centenarian who escapes from his nursing home on his 100th birthday. As he embarks on a journey, he encounters various characters and situations that lead to unexpected comedic events. The story intertwines Allan's past, revealing his involvement in significant historical events, including interactions with notable figures like Harry Truman and Mahatma Gandhi. The novel combines humor and history, showcasing Allan's unique perspective on life and the absurdity of the world around him.