Allegiant: Book three of The Divergent trilogy
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.

Allegiant was published simultaneously by Katherine Tegen Books and HarperCollins Children's Books in the U.K. Four weeks earlier, a free electronic companion book to the trilogy titled The World of Divergent: The Path to Allegiant was released online. The novel is being adapted into a two part film, the first part of which was released on March 18, 2016.

What if your whole world was a lie? What if a single revelation—like a single choice—changed everything? What if love and loyalty made you do things you never expected?

The explosive conclusion to Veronica Roth's #1 New York Times bestselling Divergent trilogy reveals the secrets of the dystopian world that has captivated millions of readers in Divergent and Insurgent.