Escape from Fortress City

"Pell, Logan, and Maddy join Uncle Colin's secret rebel society as junior insurgents. At first, they are happy to take down the system that failed them and kept them back, but when they receive intelligence of a dangerous presence in the center of Obsidian, they are faced with a decision: save the city or let it be destroyed. Against Uncle Colin's advice, the kids plot to sneak into the impenetrable heart of Obsidian to remove the danger, risking everything to save the city that turned them away"--Provided by publisher.