Nightshade Revenge By Anthony Horowitz

When his best friend Tom is abducted, Alex Rider is given an ultimatum by Nightshade – a sinister cult of assassins with a score to settle. But what twisted evil are they planning, and how is it connected to a revolutionary new gaming system? With no idea who to trust, Alex finds himself dragged into a nightmare world – where nothing is real but the game could kill you. The clock is ticking and Nightshade is closing in.