A wannabe prep girl moves to a new Washington Town far away from home, and will do anything it takes to make it to the top of the social food chain, including murder.

Agreed with the above.

I'll add that many writers often use this same description "...do everything it takes..." to no avail - it adds no detail and therefore is mostly useless in a logline. Best you describe the character as desperate so we can empathise with her desperation, otherwise (as DPG pointed out) it would be hard for the audience to empathise with a killer.

I think you are missing the hook. ?The logline needs that one extra thing to grab the reader.

Interesting, but I feel we need to know who/what is stopping her from achieving her goal.