The Case of the Frightened Innkeeper

Published in Popular Detective (May 1935) as The Saint Steps In, which is not the book with that title, and as The Frightened Innkeeper in The Saint Magazine (US - Apr. 1967). Also published in the collection The Saint Goes On.
The owner of an inn and his niece have been frightened out of their wits by strange happenings in and around their establishment, causing them to ask Templar for help.