Forget fingerprints and DNA matching – in London in 1864 the best evidence the police had to work with to track down a killer was a half-crushed beaver hat. In this forensic exhumation of the nation’s ‘first railway murder’, reconstructions flesh out archive accounts to review the conviction of German-born tailor Franz Müller for the murder of 69-year-old banker Thomas Briggs, tracked down by Detective Dick Tanner (Robert Whitelock). By today’s standards, the verdict seems as shaky as a line in dire need of engineering works.