"Gregor and the Code of Claw" is a children's fantasy novel written by Suzanne Collins. It is the fifth and final book in the "Underland Chronicles" series. The book was published in 2007 and follows the story of Gregor, a young boy who discovers a hidden world beneath the city of New York.

In this book, Gregor and his sister Boots return to the Underland, a place where humans live alongside giant rats, bats, and spiders. The Underland is facing a crisis as a group of rebels called the Bane, led by a white rat named the Rat King, is threatening to take over and enslave all the other creatures.

Gregor and his friends must decipher the Code of Claw, an ancient prophecy that predicts the coming of a warrior who will defeat the Bane. They embark on a dangerous quest to find the key to the code and stop the Rat King before it's too late.

Throughout the book, Gregor faces many challenges and learns about the power of friendship, trust, and sacrifice. He also learns about the true nature of war and the importance of understanding and respecting the beliefs of others.

The book received positive reviews for its well-developed characters, thrilling plot, and meaningful themes. It is recommended for readers ages 8-12, but has also been enjoyed by older readers who appreciate the complexity of the story.

Overall, "Gregor and the Code of Claw" is an exciting and satisfying conclusion to the "Underland Chronicles" series, and a testament to Suzanne Collins' ability to create rich and engaging fantasy worlds.