Quill Ears & the Other Earth (Archetypal Worlds, #5)

Four youths enter an other earth which appears to be a surreal version of earth. Its above world is paradisal without stress or problems, while its below world harbors a harsh reality of  a bodiless master race and human slaves. Finding unexpected alliances. including a small quilled mammal, the group must discover a way to deliver the below world. It involves exploiting the surprising weakness of the Master Race and summoning something from deep within themselves.