The Lumiose Tower was terrorised by the threat of the criminal organisation named the Team Flare, led by the evil Lysandre. And as you can see, the corrupted Zygrade, controlled by Lysandre himself was destroying the city, causing a massive chaos.

You, Serena, Clemont, his sister, Bonnie, Mairin, and Alain (led by the Gym leaders in Kalos) were searching for Ash and his Greninja to prevent Lysandre from using them for his evil plan. Ash was held hostage on the top of the Lumiose Tower.