Compartiment Tueurs - 1965 - 7/10
AKA - The Sleeping Car Murder

Tight French thriller. The locked room mystery, or here, murder in the train compartment.
Sleeper car. Six berths, one mysterious death. Strangulation.
The victim seems to have been innocent, and no one seems to have noticed.
Passengers scatter to their lives, police remain baffled.
Until those uninvolved passengers begin to meet the Reaper.
Film starts at a decent pace (ie; 1965), though momentum builds and by the finale is breakneck.
Script adroitly keeps viewers guessing throughout.