The drama revolves around the wedding of the teenager Bella to the vampire Edward.
The honeymoon produces a pregnancy that is developing at a rapid rate. The child, or whatever it is inside her, becomes the focus of the film.
By now, Kristen Stewart, Robert Pattinson and Taylor Lautner know their roles upside down.
Peter Facinelli, Elizabeth Reaser, Chaske Spencer and Billy Burke make the most of their roles - all impressive work given their lack of much screen time.
Most of the costars don't get to shine in this "Twilight," but you have to give them credit for their continuing commitment to the series.
Some of the actors, not even in the clips, are basically extras this time out.
The film has a lot to set up for what's to come in next year's grand finale, and it does that pretty well.
Director Bill Condon capably takes a romance and manages to turn it into almost a horror film as the plot plays out.
I found the movie's music overwhelming - just too much of it - but Condon believes that musical prominence helps tell stories within the film.
Overall, if you're a fan, you'll still be a fan. If you're not, you probably won't be jumping in for the fourth film when you haven't seen the first three.