Supersymmetry

Ryan Oronzi is a paranoid, neurotic, and brilliant physicist who has developed a quantum military technology that could make soldiers nearly invincible in the field.  The technology, however, gives power to the quantum creature known as the varcolac, which slowly begins to manipulate Dr. Oronzi and take over his mind.  Oronzi eventually becomes the unwilling pawn of the varcolac in its bid to control the world.

The creature immediately starts attacking those responsible for defeating it fifteen years earlier, including Sandra and Alex Kelley—the two versions of Alessandra Kelley who are still living as separate people.  The two young women must fight the varcolac, despite the fact that defeating it may mean resolving once again into a single person.

From the Trade Paperback edition.