A Timetable To Murder

The year is 1955 and having received an unexpected invitation along with pre-paid tickets, a selected group of family members have been requested to meet Great Aunt Agatha at the local railway station where they will be taken on a mystery journey which all will all remember for a lifetime.

The question is:
Whose lifetime will only last a few more hours?
Who’s going to commit the dastardly deed?
And how will they do it!!!?