You know I love me some middle grade adventures, but this is a tough one to rate and review. On the one hand — I love the idea of eggs carrying extraterrestrial living beings (ELBs) just showing up on Earth, each with a single white calling cards with a single word on it, and then being lovingly hatched, studied, and cared for by Ava's family (who interpret the words on the cards as each baby being's name). The descriptions of the ELBs are excellent — real Pokemon or Lilo & Stitch energy and details. There are a few too many for me to really hold in my head as I follow Ava through her daily care routines in the beginning or gallop along into the high-stakes adventure that makes up the second half of the book (where the "on the other hand" comes in) but this is a series opener so maybe a few ELBs will be the focus of each book. Also, Ava and Harley are a pretty good pair of new friends slash adventure buddies and have some refreshingly honest conversations about grief, mental health, and real struggles. 

But, on the other hand... the adventure gets real high stakes real fast with some disturbing scenes of the ELBs being hunted

and torturously experimented on

. And then it gets even more disturbing. Like maybe we were introduced to a character with PTSD because Ava will be dealing with that herself going forward? Except that the conclusion comes very quickly after the traumatic scene and doesn't really mention the trauma, so maybe not. Also, that conclusion, is ... odd? Or at least doesn't seem to follow the internal logic of the story? It's meant to indicate that this is a series and the story — and the extraterrestrial zoo — will continue, but it seems to directly contradict a pretty important revelation that Ava has about the zoo in general. It definitely muddled some ethical considerations about the care and keeping of the ELBs. So... it was more confusing/annoying to me than it was an effective teaser about what's to come in the next book. 

I'd recommend this one, with some reservations and a tip to definitely check the content warnings, to upper middle graders interested in delightfully weird creatures and the people who care for and protect them.