Ever World Land Of Loss by K.A. Applegate Paperback 1999 GD

There is a place that shouldn't exist.

But does.

And there are creatures that shouldn't exist.

But do.

Welcome to a land where all of your dreams and nightmares are very real - and often deadly.

Welcome to Everworld.

David, Jalil, April, and Christopher have been pulled into a world that defies everything they once believed. Wolves the size of elephants, beings who consider themselves immortals, mythological gods. Nothing is like what they're used to. And it doesn't look like they're going to find a permanent way home anytime soon.

It all started with Senna. Now she's missing. David and the others don't know if she's in Everworld. They don't even know if she's alive. Alive... in the human sense.