The final book in Mira Grant's terrifying Parasitology trilogy. The outbreak has spread, tearing apart the foundations of society, as implanted tapeworms have turned their human hosts into a seemingly mindless mob. Sal and her family are trapped between bad and worse, and must find a way to compromise between the two sides of their nature before the battle becomes large enough to destroy humanity, and everything that humanity has built. . .including the chimera. The broken doors are closing. Can Sal make it home?