The Whisper by Emma Clayton

This book is the sequel to The Roar, and I gave it a rating of four out of five. Mika and Ellie are reunited, and they realize all of the children have been trained to fight a war against the people north of The Wall. Mal Gorman has the twenty-seven thousand children sleeping until he wants them to attack, but the twins are able to mentally communicate with them. Mika and Ellie decide to capture Gorman, take control of the fortress and its defenses, and then negotiate peace between the governments north and south of The Wall. However, the plans go haywire when the children's parents discover The Secret and build a huge bomb to blow a hole in the wall separating the two worlds. The twins may not be able to stop the war and all its destruction once it begins.

This book has a dystopian setting where the humans almost destroyed all of the plants and animals. While Mika and Ellie are main characters, the author allows other characters to have important roles too. Kobi acts as a spy while helping to build the bomb for the parents, and Leo is in charge of negotiating with the government south of The Wall. I was expecting a third book in the series, because there seemed to be too many conflicts to resolve. However, the plot came to a nice resolution.