Evil sorceress Morgana summons mighty gatekeeper the Cailleach, who opens a door to another world from which hellish creatures pour forth. As Arthur and his loyal knights take up arms, Merlin discovers the only thing that will stop them is an unimaginable sacrifice.
| Title | The Darkest Hour (1) |
|---|---|
| Genres | Action & Adventure Drama Sci-Fi & Fantasy |
| Release Date | 2011-10-01 |
| Episode Runtime | 00 Hours 43 Minutes |
| Season Number | 4 |
| Episode Number | 1 |
| Production Companies | Shine TV |
