It’s the dawn of the new decade, and Detective Inspector Sean Duffy is more than happy to slam the door on the grisly ’80s, clinging to the hope that the ’90s might prove more peaceful for the people of Belfast. Duffy looks forward to embarking on his own personal new chapter, spending more time with his longtime partner, Beth, and daughter, Emma, as he switches to being a part-timer at the Carrickfergus RUC.
Before Duffy can shift gears though, a missing person report captures his attention. A fifteen-year-old girl from a seedy local caravan park has vanished without a trace. Duffy’s sense that this is more than a case of a teenage runaway is soon confirmed as he uncovers a network of lurid middle-aged men closely connected with the girl. Fearing that every second lost could mean the case remaining unsolved, Duffy urgently tries to uncover what happened to the girl—while simultaneously having to manage a mercurial triple agent. This final case for Detective Duffy looms more dangerous and twisted than anyone had first expected.