Emily aka The Doodlebug
Written by
Leslie Charteris
Copyright 1948
First published as Salt On His Trail in 2 issues of Ellery Queen Mystery Magazine (US - Nov. 1948 & AUS - May 1859) and 2 issues of Suspense (AUS & UK - Dec. 1959), then as The Saint and Emily in Pocket Book Weekly Storyteller (Aug. 25, 1949), and as The Doodlebug in The Saint Mystery Magazine (UK - Dec. 1962). Also published in the collection .
The Saint's friend's mother has been hoodwinked into buying a fake gold mine.