Without thinking, I run toward the sounds of Sierra's screams.

"Emily!" Aiden shouts and then runs after me.

Soon, the rest of the group is following. I come to a dead stop when I see Sierra. She's standing over a hole filled with a blackish liquid, tears streaming down her face and still screaming for her sister.

"Sierra," I gasp, out of breath. "What's wrong? What happened?"

"My sister." She sobs and points to the large, black hole. The ...