They came from a dying world to steal Earth's water... but they didn't anticipate resistance from the vampires, who realize the aliens' plans, if carried to fruition, 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, as the aliens also conceal their presence so the humans won't learn of their invasion already underway.