Merlin - Love In The Time Of Dragons

The wonderful Pauline Collins co-stars in this week's episode as an 'old-flame' of Gaius by the name of Alice.  A man is miraculously cured and Gaius recognises the work of his old love who he hasn't seen since the great scourge.  You see, King Uther had all people accused of using magic killed and Alice was a healer, so to save her life, Gaius sent her away.
Now she is back and working alongside Gaius and he hasn't been happier.  Then Merlin spies Alice with a creature, that he ends up working out as a mystical Manticor.  He tries to warn Gaius but he won't have any of it, thinking Merlin is jealous.
But the Manticor has Alice under its spell and wants to use her to kill Uther.  How will Merlin stop the Manticor, save Uther and keep Gaius as his closest friend?