Deadlock - Mark Walden

Otto and Raven are desperate to rescue their friends from the clutches of Anastasia Furan, head of the evil Disciples organisation. First they must track down the location of the Glasshouse, the prison where Furan trains children to become ruthless assassins. But Otto is also being hunted. The three months that Otto has spent following his 'expulsion' from H.I.V.E. have given the Artemis Section - an elite division of the American intelligence services that specialises in capturing the toughest targets and reports only to the President - an opportunity to locate him. Deadlock - the eighth book in the breathtaking H.I.V.E. series - continues the high-octane adventures of
the supremely talented criminal team, with central characters forced to question everything that Nero has taught them and to confront the consequences of life as a villain, set against the backdrop of a daring high-tech prison break where nothing is quite as it seems.