1862. A goods train is going through the Sapperton Tunnel when it hits a makeshift pen of sheep inexplicably set up near the exit. The animals are slaughtered by the impact whilst the train hits a pile of rocks and is derailed, seriously injuring the occupants. Inspector Colbeck is called in to investigate and discovers that the shepherd and his dog are missing. Stephen Ryle who owned the sheep is shocked by the occurrence which further affects him as he is a major shareholder in the Great Western Railway which has been thrown into chaos by the incident. Does someone have an axe to grind against Ryle? Or is it the missing shepherd who had made some dangerous enemies? With family grievances, embarrassing secrets and village feuds, it is not going to be an easy case for the Railway Detective.