Courtroom 302 is one of my favorite - a deep dive into the inner workings of the courts.
When I was in my first semester (in my third currently) I found that "Criminal Justice: The Essentials" was a really good book to read. It was required for my intro to CRIJ class and it was very simple and informative, especially because I had no knowledge of the CRIJ system at all.
Being a CRIJ major, I still have my book and still look back on it sometimes for my current classes. I definitely recommend it.