Rouletabille (literally roule ta bille, or "Roll your marble") is French slang for "globetrotter", one who has been around the world and seen it all.

The book reveals that Rouletabille is the nickname of 18-year-old journalist Joseph Josephin, who was raised in a religious orphanage in Eu, a small town near Fécamp.

In the novel Rouletabille meets Ballmeyer, an international criminal of great repute and many identities (a character possibly inspired by fictional Arsène Lupin).

As Jean Roussel, Ballmeyer married a rich American heiress, Mathilde Stangerson, the Lady in Black of the second novel.

Ballmeyer returns in The Perfume of the Lady in Black at the end of the story, which takes place in a castle on the French Riviera.