S1·E21 4:50 from Paddington, Part 1: The Train a Murderer Rides
Aired January 9, 2005
Synopsis
Elspeth McGillicuddy, a friend of Miss Marple, witnesses a murder on a passing train while on her way to visit St Mary Mead. The police stop investigating when they cannot find the body. Mabel persuades Miss Marple to send her on a dangerous undercover mission to find out the truth.