In Twilight: Breaking Dawn, Edward, and Bella get married and halfway through their honeymoon, Bella realizes that she is pregnant, which is impossible. Still, Bella gives birth to Renesmee, who is a half-vampire and half-human, and Bella almost dies while doing so.
Bella turns into a vampire and she starts to learn the things about living as one when Alice gets a vision of the future that the Volturi, who are the strongest and largest vampire coven out there, have mistaken Renesmee as an immortal child and are coming to kill her since immortal children are dangerous.
The Cullens decide to get as many vampires as they can to bear witness so they can at least stop the Volturi and have them hear their explanation of Renesmee so they get as many vampires as they can.
In the end, the Volturi still insists that Renesmee may be dangerous when she grows up but is then left with no questions when Alice brings another vampire hybrid which comes as a surprise since they thought that Renesmee was the only one. Still, he explains his life, and the Volturi eventually leaves.
This book is the last part of the twilight saga, and it did finish quite well, and it even binds a lot of loose ends like the one with Jacob and Rosalie.