The follow-up novel to The Boy in the Suitcase carries the same powerful sense of suspense and again uses a mystery novel format to tell a story about a social issue that will feel uncomfortably familiar to readers. In the case of Invisible Murder, Kaaberbol and Friis shine a bright and harsh light on xenophobic, anti-Muslim and anti-Romany sentiments in Europe. As in the last book, the ways in which children suffer are particularly highlighted.

I would say Invisible Murder is more finely-crafted than The Boy in the Suitcase and it does a better job of deeply involving us in all the key characters. It's also possibly more violent and intense, which makes it a more difficult read but also impossible to ignore. It's truly painful to read about the tough choices Nina Borg has to make between providing medical assistance to dying undocumented Romani children and between devoting herself fully to her own children.

Nothing is oversimplified in this story but the complex struggles the characters face and the surprising solution to the main mystery don't get in the way of the overarching social message about the dangers of racism and intolerance.