The central character is Macon Ravenwood (Jeremy Irons), who is trying to prevent his niece Lena (Alice Englert) from becoming an evil witch like her mother (Emma Thomson) on her 16th birthday. (Actually, they prefer the term "caster" as "witch" is such a harsh word.)
The other girls at school don't like Lena much because (1) she isn't blonde (2) she's kind of weird (3) she's really hot and (4) her family are devil worshippers. Go figure. There is a boy called Ethan (Alden Ehrenreich) she likes, but we're kind of afraid that she'll find out that he's really gay.
You may notice that the key cast members are all Brits or Australians, who struggle to put on southern accents. Apparently, there are no good actors in America any more. And to prove it there is Ehrenreich, who has more trouble with the accent than anybody. On the other hand, Englert is really, really good.
But the movie was enjoyable.