Murders are a rare occurrence in the UK but rarer still are those cases when the killers are not caught. But in fact one in ten murders is never solved and these are the cases that haunt us to this day. There are the cases that generate enormous publicity, such as the disappearance of Suzy Lamplugh or the slaying of Jill Dando. Cases where the police worked tirelessly through thousands of lines of enquiry but still the killers managed to slip away. Other cases are less known outside their families and communities but terrify all the same.