While on patrol, Arthur and his knights come upon the aftermath of a Saxon ambush of a caravan bound for Camelot.
Mordred spots a Saxon woman fleeing the scene and when he catches up with her he discovers it's his childhood sweetheart, a rather dishy druid girl called Kara (Alexandra Dowling) and she's nursing a wound from being shot with an arrow.
He lets her slip away, then returns later with some healing ointments he's pinched from Gaius. Merlin sees him coming back into the castle, but Mordred swears him to secrecy, stressing that the girl is harmless.
However, the next day Arthur returns to the ambush site and spots Modred's footprints in the mud and follows them to the cave where Kara is hiding. She then doesn't help her case by trying to stab Arthur.
Taken back to Camelot, she is sentenced to death and Mordred's pleas to Arthur fall on deaf ears. Eventually, Morded decides he has to take matters into his own hands to save the woman he loves.
The Drawing Of The Dark was a mighty episode, setting the stage perfectly for the series finale, which begins next Saturday.
It has to be said that Alexander Vlahos - as Morded - owned this episode and it just highlights what a pity it is that Merlin is soon to wrap up. If only we had had more episodes of this magnitude where Mordred had been allowed to shine.
He has been crafted as complex character in this show, not the usual black-hatted bad guy he is often portrayed as in films and TV serials about the Arthurian myths.
Mordred tries for the longest time in The Drawing Of The Dark to remain true to Arthur and Camelot, yet Arthur is as unwavering as Kara in his beliefs - sounding not unlike his father, Uther, on a number of occasions.
By staying true to his heart, Mordred is backed into a corner and his only course of action is to return to Morgana... and reveal the big secret he has been hanging on to for so long.