Sophia Myles needs to work on her acting
At first I thought that she was a new actress who just needed more experience, but then I went to her page and saw that she's done a lot of previous work.
Her acting consisted of looking at people and making her eyes bigger. She was able to show two emotions: happiness (smile/laugh) and sadness (crying). It doesn't take a good actress to be able to smile or cry. If there was a scene that involved something more complex to be going on such being in mental pain, but not crying, like when she was remembering her DA bf, Josh Lindsay, (The Mortal Cure), she did not pull it off at all.
If you watch the difference between when Jason Dohring's character is remembering Sarah (Sleeping Beauty) and Sophia's character is remembering Josh, it is obvious who can act and who needs more work.