Necroscope III: The Source (Necroscope, 3)

Brian Lumley's Necroscope III: The Source is a chilling, epic tale of horror and suspense that expands into science fiction as the vampires' otherworldly origin is revealed!
Psychic spy Jazz Simmons disappears while investigating a secret installation in Russia's Ural Mountains. His boss at E-Branch, Britain's ESPionage organization, interrupts Harry Keogh's search for his missing infant son to ask the Necroscope to seek Jazz among the dead.
Jazz is not dead. Captured by the Russians, he was sent through a weird portal to Starside/Sunside, a world where one side always faces a broiling sun while the other faces the frigid darkness of space. Where people survive in a narrow strip of land that neither burns nor freezes. Where the vamphyri hunt. Starside/Sunside is the vamphyri homeworld.
His last, desperate psychic message to Harry: the vampires are preparing to invade Earth.
Harry must do battle on the vampire homeworld, but on a planet were few people ever truly die, there is no army of the willing dead to battle at the Necroscope's side. His greatest ally is his son, Harry Junior, mysteriously grown to adulthood seemingly overnight. Together, the two men have tremendous power...but Junior is keeping secrets that imperil father, son, and all of Earth.
Necroscope III: The Source is the third volume in an entertaining series that has enthralled millions of readers with its very different look at vampires and vampire hunters, at the dead and the living and the worlds they share.