Stakes.

Imagine a parallel earth where vampires have cut a swath through humanity. The disease is so bad, the ravenous bloodsuckers begin feeding on each other. Three surviving humans create a jump gate to our earth. But, Alyssa, Queen of the Vampires, and her evil bodyguards use the gate to come to our earth as well. They arrive to feed and breed. Now, the number of vampires here is growing and the humans are running out of time!