Audio. This is a mix of children‘s lit, historical fiction, and mystery. I listened to the audio, and overall it was ok. I did lose focus (as I seem to with audios more often lately) a few times, but the story was ok. There was a short author‘s/historical note at the end, though being a kids‘ book, it didn‘t go into detail. Even with only an “ok” rating from me, it might still be a fun series to continue