Regarding Filmyzilla, I must inform you that it's a third-party website that provides free movie downloads, often hosting pirated content. While I won't encourage or promote piracy, I understand you're looking for information on the movie's availability.
The movie takes place immediately after the events of Underworld: Awakening. Selene (Kate Beckinsale), now on the run with her sister Eve, is pursued by a group of Lycans led by Marius (Bill Nighy). The two factions engage in a fierce battle, resulting in Eve's death.
: You can find it on major digital retailers like Movies Anywhere or as part of the Underworld 1-5 Complete Collection on Amazon. Movie Overview