Help me remember the title of a children's book series?

The Land of Elyon books by Patrick Carman. The first book is The Dark Hills Divide

"Upon arriving at the Renny Lodge (Named after Warvold's wife Renny Warvold), Alexa is greeted by Ganesh, the mayor of Turlock and by Warvold himself. After going up to her room, Alexa uses a spyglass, stolen from her mother, to look over the walls from her window. She is interrupted by Pervis Kotcher, head guard of the Turlock gate, who takes the spyglass from her. Fortunately, Warvold comes just then (Pervis hides the spyglass) and takes Alexa for a walk which, as shown in the beginning of the book, ends in his death. Before getting help, Alexa takes a silver key from the locket around Warvold's neck. During Warvold's funeral Alexa sneaks to the library. While there, she drifts off to sleep in her favorite nook. She is awakened by Pervis, who breaks her spyglass before returning it. At dinner Nicolas (Warvold's son) tells Alexa about his mother Renny's interest in the art of Jocastas. That day, when Alexa is in her favorite nook again, she discovers that the medallions which the library cats Sam and Pepper have hanging from their collars, have Jocastas etched on them. Alexa is successful in looking at Sam's but receives a nasty scratch when she attempts to look at Pepper's.

Later on, Alexa uses the silver key to open a passageway hidden behind her favorite nook. At the end of the passageway, outside the wall, Alexa is greeted by a short man named Yipes, who seems to have been waiting for her. Alexa follows Yipes up Mount Norwood and comes to a glowing pond. Inside the pond, she finds a green stone. Once she puts it in her leather pouch, Yipes takes her to his house. Waking up from her sleep, Alexa finds that she has the ability to talk to animals. Darius, a wolf separated from his family, leads her to a tunnel under the walled road between Lathbury and Bridewell. At the end of the tunnel, Alexa discovers that the convicts of Ainsworth inhabit The Dark Hills. Once she is back outside, a rabbit named Malcolm takes her to the forest king Ander, a grizzly bear. Ander tells Alexa that she can talk to animals as long as she has the green stone with her and is outside the walls. He also tells her that the convicts living in The Dark Hills are planning to attack and take over Bridewell. The leader of the convicts is someone the convicts call Sebastian, an escaped convict posing as a citizen of Bridewell. At the meeting Alexa meets Murphy (Squirrel), Beaker (Raccoon), Henry (Badger), Picardy (Female Black Bear), Boone (Bobcat), Odessa (Darius's wife) and Sherwin (Darius's son).

The day after the meeting, Alexa is sent back through the passageway she came from. Back in the library she learns that Sam and Pepper are traitors. At her arrival, Silas, who Mr. Daley promotes as his personal mailman, asks her where she had gone. Alexa lies and says she was playing a game."