The Saint Plays with Fire

The Saint attempts to rescue a man from a burning manor house, only to be unable to reach him in time because his bedroom door has been locked and the key taken away. When he discovers who the (now dead) young man was - a prominent Socialist agitator - and that the rest of the house party are staid right wing pillars of society, Simon begins to feel that something serious is going on. The involvement of the Sons of France soon becomes clear, but not why they are connected with the murder...