This article is about the episode; for details about the titular asteroid see Helios-685 (asteroid).
- "Prevent Helios and we prevent the beginning of The Fall. That was The Director's calculation that started this whole thing."
- ―Grant MacLaren
|For a complete plot of Helios-685, go here.|
- Eric McCormack as Grant MacLaren
- MacKenzie Porter as Marcy Warton
- Nesta Cooper as Carly Shannon
- Jared Abrahamson as Trevor Holden
- Reilly Dolman as Philip Pearson