The Marco Effect by Jussi Adler-Olsen

Things are chaotic as usual in Department Q of the Danish Police.  Detective Carl Morck, who has turned his disgrace and banishment to the basement as the man in charge of cold cases, is torn between two women.  Assad, his assistant with the air of mystery, has just returned from a case that left him injured and in need of rehabilitation.  Rose, the cranky secretary who wants to be an investigator also, has taken up with a young detective who is clueless but has connections upstairs.  Worst of all, the head of the detective bureau is leaving and his replacement has never liked Carl at all.  His first act is to send Gordon, the clueless one, down to be a new member of Department Q and to report back to him everything Carl and the crew are doing.

Marco Jameson is a fifteen year old boy who wants more.  More than his life as a con man and thief, part of a gypsy crew that is let off downtown each morning to pick pockets and steal from anyone they can.  His uncle, Zola, is the head of the clan but that blood relation means nothing to him.  He views everyone as mere tools to help him get more money.  He even cripples one of the young girls in the crew to make her a suitable beggar.  When Marco stumbles upon the grave of a man he is sure Zola has killed, he sees his chance.  He runs away and tries to find a way to contact the police.

In the meantime, Carl is caught up in a case involving a missing man.  The man had gone on a trip for his bank to Africa where they were administering a grant to provide aid.  But his trip had gone sour and he had returned a day later and then disappeared.  What happened to him and why was he gone?  Carl works the case and suddenly it becomes clear that Marco holds the key.  Department Q springs into action to find Marco but it's soon clear they are not the only ones trying to find him.  The others want nothing more than to kill this inconvenient witness.  Can Carl and crew find Marco before his enemies can?

This is the fifth novel in the Department Q series.  Carl, Assad and Rose are the same supposedly incompetent investigators that manage to solve the cases that everyone else has given up on through sheer determination and spite.  The addition of Gordon, whose youth, naivete and attraction to Rose define him, is a development that can provide new avenues for the group.  This book is recommended for readers of mystery novels.