Second in the Department Q series, The Absent One takes a darker turn The Keeper of Lost Causes. After solving a high-profile cold case, Carl, who is just back from a holiday, has a mounting pile of cases. As ever, Assad is eager to get to work on another case. Despite his reluctance, Carl is intrigued by a file that suddenly appears on his desk. Although officially, the case is closed, Carl is soon convinced that something was missed. As Carl and Assad investigate the murder of a brother and sister, they soon find that there are other cases, seemingly related to the perpetrators. Unfortunately, those in question are high society players with a lot of backing and clout. It soon becomes apparent to Carl that someone is pulling strings to thwart his investigation, including making oblique threats and whispering in the ear of the police chief. It is also apparent that these crimes were carried out by a gang of students for the sheer pleasure of committing them, adding to the shocking nature of the crimes. Time is of the essence, as Carl and Assad hunt for Kimmie, one of the group who is no longer associated with the other 3 suspects. Once a crucial part of the gang, Kimmie is now on the run and hiding from the other three who want to see her dead. Carl and Assad are frantic to find her first. Add to all of this, a new assistant, Rose, who Carl finds overly irritating. Especially since she and Assad seem to get along so well. And a heavy request from his former partner, Hardy, for Carl to allow him to be moved and cared for at Carl’s instead of the hospital. Despite the darker nature of this book, Adler-Olsen manages to inject some moments of humor, keeping the book from being too macabre.