"The Absent One" is a crime novel by Jussi Adler-Olsen, part of the Department Q series. The story follows detective Carl Mørck and his team as they investigate a cold case involving the mysterious deaths of two wealthy siblings. As they dig deeper, they uncover dark secrets and a web of deceit that leads them to a dangerous criminal. The novel explores themes of justice and morality, highlighting the complexities of human relationships. With its gripping plot and well-developed characters, "The Absent One" keeps readers engaged while addressing the impact of past traumas on present actions.