In this second episode, The Detectives, a look at the evolution of police detective work, from its early beginnings in the 19th century to landmark cases of the 21st. The testimony is often moving and gives a real insight into what it takes to be a detective. Many recall dealing with the emotional baggage that comes with the job. From crime scenes to unsolved cases, the pain is often etched on their faces as they relive the moments that had the biggest impact on their careers and lives. Some of those moments lie within two of the most famous cases in Scottish police history, the 'World's End Murders' of two 17-year-old girls, Helen Scott and Christine Eadie, in 1977, and the murders of young schoolchildren by Robert Black in the 1980s.