Mekhennet writes about her life and work as she grows up in Germany, later becoming a reporter for The Washington Post and The New York Times. She discusses how international incidents affected her and her family; anti-Muslim sentiment in Germany, for example, made her fearful for their safety. Instead of leaving the country and trying to find somewhere else to live, she decided to face the problem and try to make things better by becoming a journalist. 

One thing she charts in her book is the rise of Islamic terrorism. She talks about many events, starting with things happening in the late 70s and continuing on until 2016. She also reaches back further into the past through the experiences of her parents, Turkish and Moroccan immigrants. She shows how religion was twisted to justify violent behavior. She also discusses the role of Western involvement in changing the direction of various countries in the Middle East. These things affected her life directly. As a review in The New Yorker says,

"Mekhennet says that she is someone who narrowly escaped being radicalized herself—owing to the influence of her involved parents and family friends. Instead, she turned to uncovering what motivates the most fervent of believers in jihad, and how they became so unrepentant."

She's passionate about finding out what drives such hate.

Mekhennet also writes about the role of the media in disseminating information and creating narratives. For example, she accuses the Western media of convincing people that the Arab Spring would result in democratic governments taking over regimes in the Middle East quickly. When that didn't happen—which was to be expected since such a process takes a long time and many cultural changes—it disoriented and dissatisfied people. The media also chooses to focus on or ignore certain stories to create its own narrative. There's also a discussion of access to direct sources. Mekhennet is better able to access people like Al-Qaeda commanders because of her background; many Western journalists have no direct contact with people in jihadi groups.

Another theme is radicalization. Mekhennet shows how young people respond to different stimuli that make it easier to radicalize them and convince them to join jihadis. One example of this is her friend's nephew, Pero, who leaves Germany to go to Syria and join a jihadi group. His relationship with his father and the anti-Muslim sentiments in the West make him ripe for radicalization. Though she's saved, Mekhennet notes throughout the book that many others are not—and that radicalization cannot be stopped unless we're willing to face and address what causes it. 

The problems of cultural misunderstanding are another theme in I Was Told to Come Alone. Because Middle-Eastern and Western cultures don't fully understand each other, it's easier to sow hate and discord. If each works harder to understand and accept positive aspects of the different cultures, society would be better for it. People are less likely to understand and relate to those outside their own culture, which also makes it harder to see the others as real people. Mekhennet recognizes this and recognizes that she's part of both cultures and can therefore help people understand how to bridge them.