What is the fine-grained topic of the following text: We discussed Mattos’ new book, “City Of Death: Humanitarian Warriors in the Battle of Mosul.” He wrote the book with Scott McEwen, who also wrote New York Times best-seller, “American Sniper,” with Chris Kyle. Only return the topic.
Discussion on Mattos' new book, "City of Death: Humanitarian Warriors in the Battle of Mosul."