The book is well researched, it presents events with historical accuracy without spending time on nuances which will bog down the story. I enjoyed that the author tried to make the story flow presenting relevant facts intertwining with the narrative.
The strength of the book is the written descriptions of the way immigrants had to live in Paris during World War II and what it took to survive, or even eat once a day. The descriptions of the harsh life of immigrants, especially Jewish immigrants, during that time are heartbreaking and show how easily a boy could turn assassin.