The team investigates the case of a badly burned young woman, Sian Jenkins, who is found dumped two years after she was reported missing. DNA underneath her fingernails is discovered to be that of a fellow missing person, Josie Wilson, who disappeared in 2005 at the age of eight. Jack suspects that Sian's father, Neil, may have had a part to play in her disappearance after evidence suggests that he accosted a young homeless girl, during his rounds as a charity worker. Martha, however, isn't convinced, and soon evidence suggests that Josie's father, Mike, may infact be the abductor, and the discovery of a baby in his cellar unravels a string of horrific events.