Fred is a sixth-grader reeling from the loss of his beloved dog, Casey. Every day he walks home from school bouncing Casey's old worn-out tennis ball. One day, the ball falls down a sewer grate, and Fred can't bear to leave it down there. He pries open the grate and stumbles down. Through the sewer, Fred enters a parallel universe: Casey is alive, his mom and sister are happier, and there's a version of Fred who's happier too. Spending time with Casey,...