This book is a bridge between the main 39 Clues series and the new series, Cahills vs. Vespers. It contains four stories, each taking place at a different point in time, that explain key events of how the two families are linked. In the first one, we also see how the four siblings who give the names to four Cahill branches grow apart and how Gideon Cahill dies.

Out of the four stories, the important ones are the first one and the last one. The other two are nice, but not particularly important. As I haven't started the new series yet, I don't know if those two stories may be important later though.

As the stories are so short, there isn't much character development in any, except for the last, which is the only one with Amy and Dan in it. I liked to see how Amy finally starts acting as a leader. It was something that was hinted in the first ten books, but she finally realises that she can't run away and that they will have to train instead of relying so much on luck.

There was one thing that felt a bit like a plot hole in this book, but I hope that it's explained in the series. Several members of the Cahill family have been following the clues for a while, but none of them have noticed that the Vespers were after the same clues? Also, how is it that the ring was never mentioned until now? As it's shown in Grace's story, the Vespers know of it and want to get it, so it's reasonable to think that the different Cahill branches know if it as well. It would be rather stupid not to spy on your enemies too, if you've been spying on your own family for centuries. Obviously, the easiest explanation is that the writers hadn't though of this new plot yet, but I hope to see an in-story explanation. ( )

I liked the earlier historical set up more than the actual series. ( )

I liked the earlier historical set up more than the actual series. ( )