A body is found on board the last steam train after festive trips have finished on the heritage railway near Grimsby.
Once the Police arrive and seal off the area, they wait for the arrival of DCI Garner and DS Brierton. They arrive directly from a Christmas party to investigate what looks like another murder mystery for them.
Another question that requires answering is when the Crime Scene Manager, Rachel Howton also arrives, has she come from a party too? or can her appearance give everyone a deeper insight into her real personality?
As they investigate, they uncover suspects, all of whom have motive and opportunity to carry out the murder.