The forerunner of all serials, What Happened to Mary was a series of twelve monthly one reel episodes, each a complete entity in itself, revolving its immediate dramatic and melodramatic problems within the framework of a single episode and designed more for story and suspense situations than action.
Unfortunately the movie What Happened to Mary is not yet available on HBO Max.
| Writing | Horace G. Plympton | Writer |
| Directing | Charles Brabin | Director |
