PORTAL: Something in the Sky

"I hear it too," Lizzy said. "It's coming from up there." She pointed towards the sky. They all looked in that direction and heard a strange roaring noise that seemed to be approaching them. "What do you think it is?" Sarah asked. "I'm not sure," Seth answered. "It almost sounds like ..." Before he was able to finish, the four of them watched as the source of the noise flew down towards them. It was ...