Allegiant is a science fiction novel for young adults, written by the American author Veronica Roth and published by HarperCollins in October 2013. It completes the Divergent trilogy that Roth started with her debut novel Divergent in 2011. The book is written from the perspective of both Beatrice (Tris) and Tobias (Four). Following the revelations of the previous novel, they journey past the city's boundaries to discover what lies beyond.