Kate Thompson brings her Missing Link science fiction trilogy to a close in an absorbing finale that moves back and forth between two narratives. In one, teenager Christie, his half-brother, Danny, and the other human and talking animal inhabitants of the insular northern Scotland research community known as “The Fourth World” have an unwelcome visitor. Christie’s journal entries chronicle the mysterious arrival and ever-more-threatening activity of a clearly sentient but amorphous being that has taken over their computer lab. In another, teenager Nesa is on the run after the Dogs attack her Cat community. She is soon joined by Farral, one of the Dogs, a young man whose ideas are both upsetting and surprising. Farral wants to work with Nesa to find a way for the Dogs and Cats to live in peace. Accompanied by the talking crow Yorrick, and followed by a pack of Grunts, human-like creatures who don’t speak, the two head north, following rumors and information passed on by the birds of a community of humans who are neither Cat nor Dog. The two start with an uneasy truce and gradually build trust and friendship, but their contradictory creation stories form an unspoken barrier between them. The Cats are descended from Atticus, the Dogs are descended from Ogden, and each set of beliefs asserts its followers’ moral superiority over the others’. Thompson’s two separate and compelling narratives remain disparate until the startling and satisfying conclusion, which weaves the stories together in a novel that illuminates the profound and transformative power of language, which is the seed of great accomplishment, and the source of both division and unity in the world. (Age 12 and older)