The New York Times and internationally best-selling Danish crime writer Jussi Adler-Olsen returns with the third thriller in his exhilarating Department Q series.

Detective Carl Mørck has received a bottle that holds an old and decayed message written in blood. It's a cry for help from two young brothers, tied and bound in a boathouse by the sea. After floating in the ocean for years before turning up, the bottle sat forgotten, unopened, on a police department windowsill, before the seal was cracked and the gruesome message, written in Danish, was analyzed. Could it be real? Who are these boys, and why weren't they reported missing? Could they possibly still be alive?

Carl's investigation will force him to cross paths with a woman stuck in a desperate marriage: Her husband refuses to tell her where he goes, how long he will be away, what he does while he's gone - or even what he does for a living. Isolated after choosing him over family and friends, she waits for days on end, and when he returns she must endure his wants, his moods, his threats. But enough is enough. She will find out the truth, no matter the cost to him - or to herself.

In this heart-pounding thriller, Carl and his colleagues Assad and Rose must use every resource available to uncover the horrifying truth set adrift in that bottle all those years ago.