Dun, dun, dun!((Yeah, you were supposed to say that out loud while playing a bass drum. :P)) 
 The siblings Amy and Dan Cahill return in the 3rd book of the series Cahills Vs. Vespers. Also returning are the brothers Jake and Atticus Rosenbloom, along with the Cahills captives. The main plot in the book? Find Atticus, free him, and figure out what it is that Vesper 1 wants now. Complicated? Just a smidge. 
 What I love in this book is the plot and character development. The plot is just amazing, and just....Wow. Amy's character also turns into the Cahill leader that they need in order to save the captives. Something else I enjoyed was that the Dan from The 39 Clues original series showed a little, which made me smile. 
 I was seriously wondering if the texts Dan was getting were really from, well, him. (view spoiler)[That's right! I'm not tellin' who they might be from! Read the books, dude. (hide spoiler)] Then at the end, we find out and I'm just like: "Whoa, seriously?! Whoa, just...No way!" Yep, just like that. 
 This book is just the right length for a 8-year-old. Of course, he or she would need to read the original series in order to understand it and not worry about spoilers. Though, they need to be able to handle reading about explosions, captives, and blood. Otherwise, they'll need to wait until they're a bit older. If your kid doesn't like reading, read the first series to him/her, then read this one. By the time you get the first book in Cahills Vs. Vespers, I would think that he or she will be reading them willingly. 
 5 stars. It's short, but that's my opinion because I'm a teenager. It's the perfect length for younger readers. 
 Recommended to people who read the original 39 Clues series and ages 8-11. If your kid can handle explosions and manage reading about some blood, then this is something you should check out.