Question: is divergent the first book in the series

Answer: Yes, The Divergent trilogy is a series of young adult science fiction adventure novels by American novelist Veronica Roth set in a post-apocalyptic dystopian Chicago. The trilogy consists of Divergent (2011), Insurgent (2012) and Allegiant (2013). A related book, Four (2014), presents a series of short stories told from the perspective of one of the trilogy's characters. And a newly added short, We Can Be Mended (2018), serves as an epilogue five years after the events of the trilogy from the perspective of the same character as the previous add on.