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 9, Part 1 of “Caliphate,” in which Rukmini speaks to an ISIS detainee who challenges her to find the girl he enslaved. For more information about the series, visit nytimes.com/caliphate.

This episode includes disturbing language and scenes of graphic violence.