The Greystones are back for this second installment in the series. It’s been 12 days since Mrs. Greystone and Ms. Morales disappeared in an alternate universe full of corruption, sabotage, and alternate, more sinister versions of themselves. Emma Greystone has been working tirelessly to crack the code their mom left for them to find her, but after close to 400 tries, she still hasn’t gotten it. As they begin to figure things out, it becomes clear that to rescue they’re going to have to go back to the other universe. Once there, they realize things are even worse than they’d suspected, and they can’t trust anyone.

You definitely need to read the first book to understand the plot of this book. I love the combination of mystery, science fiction, and math in this series — and who doesn’t love secret codes? There are fun twists in the plot, but it isn’t overly complicated so young readers won’t be lost. Recommended for purchase for most collections, especially where middle grade mystery is popular. This series is great for 4th-8th grade readers though the plot would be appropriate for advanced younger readers too.

Reviewed by Jessie Trafton, Skidompha Library, Damariscotta, ME