Immediately below is the cover of The World-Famous Nine, which was done by Chloe Bristol. The other illustrations further below, which come from the inside of the book, were done by Kristina Kister. All of the illustrations exist under copyright of Chloe Briston/Kristina Kister/Christy Ottaviano Books/Hachette.

Here is the overview of The World-Famous Nine that can be found on the back of the book itself:

Zander Olinga’s grandmother is the owner of the fabled Number Nine Plaza, the spectacular nineteen-story skyscraper. The Nine, as it’s called, has everything imaginable, including a massive Ferris wheel on its rooftop, monorail tracks suspended from its ceiling, and twenty-five glass elevators. But there’s something evil looming in the shadows, and strange accidents start befalling the guests. When Zander and his friend Natasha come across a series of inscriptions hidden throughout the walls of The Nine, they discover that the clues will lead them to a magical object which protects the store’s very existence. With the future of The Nine on the line, the pair are determined to recover the mysterious object before the luxury plaza and its many guests are destroyed. 
 

Here are some pictures from the book: