Fascinating Long Read: Skyping With The Enemy
"I went undercover as a jihadi girlfriend..." writes the pseudonymous French journo, Anna Erelle.

Her book about this, In the Skin of a Jihadist: A Young Journalist Enters the ISIS Recruitment Network, seems to be in Audible format only in the USA. (On second thought, it seems to be mislabeled as Audible, and seems to be in paperback.)