Vampires Vs. Aliens

They came from a dying world to steal the Earth's water, a scarce but necessary resource they need to survive, but they didn't anticipate resistance from the vampires, who learn the aliens are setting up plants in coastal areas to take the Earth's water. The aliens' plan would doom the human race... And with no humans or other life left on Earth, the planet's furtive vampire population would be deprived of its sole food source. Now the vampires must wage a secret war against the invaders while hiding their own existence from the humans.