The New York Times has introduced a documentary audio series that follows Rukmini Callimachi, who covers terrorism for The Times, on her quest to understand ISIS. Today, as a special episode of “The Daily,” we offer Chapter 4 of “Caliphate,” in which a new recruit proves his worth and gets invited to a secret meeting. For more information about the series, visit nytimes.com/caliphate.

This episode includes disturbing language and scenes of graphic violence.