*You don't need to watch the movie to read this*
Beatrice Swan or Tris is Isabella or Bella Swan younger sister.
They did everything together. Share secrets, clothes, family.
Until they meet the Cullens. And come to find out they are all vampires. That's when Tris's life turned around. Bella met Edward Cullen and they became a cute couple.
At Edward's family baseball game four nomads (homeless vampires) came and runed the game. James a tracker caught a scent of Bella and Tris and he was after them.
But the 4th vampire is Tris's soulmate. His name is Aidan Turner.
The whole story starts from there.