At times I'm not sure if it's fair for an "old lady" to review a middle-grade book ... but I have absolutely loved some middle-grade and YA books.  I think I would have liked this more in my younger years. 

This was a cute story, an addition to the series with a focus on Ruby. We learn more about both her present life, and her past. While Ivan and Bob make appearances, this is Ruby's book. 

Told in the same format ... no numbered chapters, but a header (word or phrase) and then anything from a couple sentences to a couple paragraphs relating to that header, moving the story forward. 

I borrowed both the audio and the Kindle copy from the library. There are cute illustrations, in the book and at the start, showing elephant body language, and the "glossary" of terms like in the other books. The narration was good.

Middle-Grade May!