The Roar Series by Emma Clayton

Mika and Ellie live in a future behind a wall: Solid concrete topped with high-voltage razor wire and guarded by a battalion of Ghengis Borgs, it was built to keep out the animals, because animals carry the plague. At least that's what Ellie, who was kidnapped as a child, has always been taught. But when she comes to suspect the truth behind her captivity, she's ready to risk exposure to the elements and answer the call of the wild. Listen... moreMika and Ellie live in a future behind a wall: Solid concrete topped with high-voltage razor wire and guarded by a battalion of Ghengis Borgs, it was built to keep out the animals, because animals carry the plague. At least that's what Ellie, who was kidnapped as a child, has always been taught. But when she comes to suspect the truth behind her captivity, she's ready to risk exposure to the elements and answer the call of the wild. Listen. Can you hear it? She's strapping on her headset, jumpstarting her Pod Fighter, and--with her capuchin monkey at her back--she's breaking out! less

Listen-can you hear it?The explosive sequel to THE ROAR!Suddenly alert to the microchips implanted in their brains, the army of stolen children revolts! But the response of the tyrant Mal Gorman is swift and brutal: He quickly quells the mutiny, sweeping up the fleeing children in spiked nets like so many trapped fish and dragging them back to their training camp... moreListen-can you hear it?The explosive sequel to THE ROAR!Suddenly alert to the microchips implanted in their brains, the army of stolen children revolts! But the response of the tyrant Mal Gorman is swift and brutal: He quickly quells the mutiny, sweeping up the fleeing children in spiked nets like so many trapped fish and dragging them back to their training camp. Juiced by potent Everlife pills, the once cadaver-like Gorman has chemically reversed the aging process; his diabolical mind is now powered by the body of a teenager. But psychic twins Ellie and Mika can read his every evil thought, and they refuse to let him wage his battles. Using their mutant powers, they abduct Gorman and take him beyond The Wall, to the wildlife he so fears. Before all-out war erupts, the brother and sister are determined to reconcile humankind with nature -- and to free the captive children. less