Merlin's Vow (The Camelot Inheritance ~ Book 3): A mystery fantasy book for teens and older children age 10 -14

Merlin’s Vow : A thrilling mystery adventure book - with more than a dash of fantasy and action - for teens and older children age 10 – 14.
The magic is moving, but Tamar Tamblyn - one of Cornwall’s four teenage Guardians - is stranded at Trezion’s Christmas fair, miles from her fellow Guardians. Will Arthur, Nick or Gawain reach her before their enemies close in … or will the Ice lady claim her prize? Who is the mysterious Dr Columbarius? Where is Oakwood Manor? And since when did time travel mess with molecules – or become quite so dangerous?

This is the story of four teenagers, some ancient knights and a dragon (a very tiny one), pitted against time-defying enemies. Camelot is calling.