A Page of Secret History

Published in The Royal Magazine, February 1921. 6th story in the collection The Luck of the Secret Service.
In Rome to investigate a communist agitator, Claud Heathwaite is stunned to discover that the man was really a notorious Soviet spy named Filodor, wanted in several countries including Italy. Heathwaite wonders what mischief would bring the man back to a country where, if apprehended, would put him away for the rest of his life.