The "Firefly of France" is an elusive master criminal of uncertain loyalties. When the Firefly disappears from view with a satchel of important government documents in his possession, his sister Esme Falconer is suspected of beings in cahoots with him. Dashing aviator Devereaux Bayne believes in Esme's innocence and accordingly dons civilian garb and heads to Paris' Latin Quarter to get the low-down on the Firefly's whereabouts.
| Actor | Role |
|---|---|
 Wallace ReidDevereux Bayne | Devereux Bayne |
 Ann LittleEsme Falconer | Esme Falconer |
 Charles OgleVon Blenheim (aka Jenkins) | Von Blenheim (aka Jenkins) |
 Raymond HattonThe Firefly | The Firefly |
 Winter HallDunham | Dunham |
 Ernest JoyAide to Von Blenheim | Aide to Von Blenheim |
 William ElmerAide to Von Blenheim | Aide to Von Blenheim |
 Clarence GeldartAide to Von Blenheim | Aide to Von Blenheim |
 Henry WoodwardGeorges | Georges |
 Jane WolfeMarie-Jeanne | Marie-Jeanne |