A few months ago, Gregor and his 2 year old sister Boots were sucked into the Underworld. There giant Rats, Cockroaches, Bats compete, along with Humans to survive and thrive in a vast world of caves, underground rivers and seas.
After rescuing his missing father, Gregor and his sister return to their home in New York City. But on a sledding trip in Central Park, Boots is kidnapped and Gregor has to go save her.
It is not too long before we find out that Boots was kidnapped for her own safety by the Cockroaches (who are devoted to Boots) to save her from the Rats that are trying to kill her.
This is all a part of yet another prophecy and Gregor now has to fulfill his part in the prophecy. He is told he must kill The Bane, a giant warrior rat that has been foretold to rule.
Gregor is not excited to be sent out to kill a giant rat and less excited to put Boots in danger again. But he has to follow the prophecy.
Similar to the first book, this moves very quickly. Although 309 pages, it feels much shorter and before you know it the quest is over and Gregor has to deal with the ramifications. In many ways the epilogue after the end of the quest is as interesting as the rest of the book. It is all about what happens when things do not happen according to plan.