The listing, Brave the Betrayal (Everworld #8) by Katherine A. Applegate has ended.
Ever since they became trapped in Everworld, David, Christopher, April, and Jalil have encountered a lot of weird things. But their newest adventure is their oddest yet. They're trapped in an area totally messed up even by Everworld standards - it's a place that's upside down! Why are they there? Well, they angered a bunch of African gods by refusing to offer up an animal sacrifice. But the four teens refuse to give in to the gods, even though Senna, the witch who got them trapped in Everworld, urges them to do so. David, Christopher, April, and Jalil may not be on the good side of the gods, but they have their real world smarts - so they have one advantage on their side. Now they just have to find a way out. I highly reccomend this book if you enjoyed the first seven Everworld books.