Stephenie Meyer, whose books inspired the "Twilight" movies, now presents a new way for true love to struggle against itself. In the "Twilight" world, characters were invited to become vampires to share more fully the lives of those they loved. "The Host" presents a possibility that, if anything, is a deeper commitment. Earth has been invaded by a race of "souls" who inhabit human bodies, stripping them of their memories and identities. It's the way the alien race survives and spreads.