Gregor and the Marks of Secret #4 by Suzanne Collins

This book is the fourth in The Underland Chronicles series, and I gave it a rating of five out of five. Gregor is talking to Luxa when she is given a gold crown from the mice. The crown is a signal that the mice need immediate help, so Gregor and Luxa set out to discover what is going on. However, they find a dead mouse at the meeting place and can't find mice living anywhere else. They've disappeared. When a basket of mice babies is found and brought to Regalia, the duo once again sets out in search of the missing mice. This time, they find a mark on a cave wall and are informed that it means death. They return to the treacherous jungle but are forced to travel underground instead of heading home. The secret tunnel leads them to a terrifying discovery about the plight of the mice. The entire population of mice, and all other living things in the Underland, may be doomed if Gregor and Luxa don't do something soon!

It's been interesting in this series how the author keeps Gregor and Boots in every plot, but the other characters come and go. This book sees the return of a few characters found in earlier plots, and the relationship between Gregor and Luxa is changing. The theme of this book also explores the notion that the only way to have peace is through the use of war. A character in the previous book said that nothing good ever comes from war; it only creates more anger. Gregor and Luxa must rethink this idea. The resolution of this plot seems to lead right into a major battle for Regalia in book five.