Like every other show out there The Secret Circle deals with teens wrestling with their abilities and their relationships, the latter be the the result of a supernatural skill set that brings students together, or typical feelings of young love.
So the pilot lays out the blue-print for the show. Cassie Blake (Britt Robertson) moves in with her grandmother in small town Chance Harbor after a mysterious fire killed her mother (which may not be so mysterious after all). There she meets this group, the witches and finds out she is one too, which is hard for her to believe. Also she feels a certain attraction with Adam Conant (Thomas Dekker). I suppose the synopsis is good enough.
So Britt Robertson as Cassie has definitely laid the foundation for the character. She plays young, shy, naive and strong willed rather nicely. Phoebe Tonkin as Faye, well she is the mean girl and she knows how to use her powers. Although it is good to have someone as rational and level-headed as Diana (Shelley Hennig) but to balance out the quota someone like Faye is needed who doesn't have qualms about using her power as she sees fit and tends to go wild.
Very little is shown about Nick (Louis Hunter) besides the fact that he is her neighbor and their windows are adjacent. Melissa is also not given much space besides the point that she is Faye's partner in crime and holds some sort of a secret.
The most aspect of the show is definitely this inter-generational war that is going to be a major factor. Something had happened 16 years ago - some "accident" occurred and many deaths took place as a result. There is a rather rich and meaty past here which is somewhat revealed during the interaction between Jane Blake and Dawn Chamberlain. So Diana's dad and Dawn seems to be conspiring together. The Circle will take care of it without knowing it.