Last Train to Lime Street

As the midnight train from Manchester to Liverpool approaches the city, it hits the body of a man. After the police look into the case, they learn that the man was a well-known movie director - of the adult variety.
Soon, they find out that the man''s list of enemies is almost as long as the railway line from Manchester to Liverpool, with two ex-wives who both have a motive for murder.
But is his murder personal or professional, and who is the killer?