The Messengers by Margaret Peterson Haddix

Summary:
As book three of the Greystone Secrets series opens, the Greystone kids have their mother back from the evil alternate world, and so does their friend Natalie. But no one believes the danger is past.
Then mysterious coins begin falling from unexpected places. They are inscribed with codes that look just like what the Greystones’ father was working on before he died. And with the right touch, those symbols transform into words: PLEASE LISTEN. And FIND US, SEE US, HELP US. . . .
The coins are messengers, telling the Greystones and their allies that their friends in the alternate world are under attack—and that the cruel, mind-controlling forces are now invading the better world, too.
After another spinning, sliding journey across worlds, the Greystone kids must solve mysteries that have haunted them since the beginning: what happened when the Gustanos were kidnapped, what created the alternate world, and how a group of mismatched kids can triumph once and for all against an evil force that seems to have total control.

Review:
The Messengers is the third and final book in the Greystone Secrets trilogy. I really liked the first two books and I actually reread them before finishing the series with this conclusion. 
We are still following the three Greystone siblings, Chess, Emma, and Finn. They tell us about how their mom’s double knocks on their door with her three kids that were just like Chess, Emma, and Finn, but maybe they actually weren’t. The two families work together to change things for the better before the mayor takes over both worlds.
I really loved this book and this whole series. I’m glad I reread the first two before this one because the series as one long story is a good one, but also each book is its own great adventure. This finale was no different. The kids faced tough challenges and had to think quickly and cleverly.
Overall, I will definitely be keeping an eye out for more new books by Haddix and probably even rereading some of her backlist.

Keep on reading lovelies, Amanda.