Reaper: A Horror Novella - Reaper, #1

How do you fight a monster?Halloween night, 1992. Promised the allowance he's always dreamed of, Gregory has to babysit his little sister Imogen and hand out candy. That was before the basement door opened on its own. Before the strange door appeared in the basement. Before Imogen was taken from him by that terrifying monster. Now, Gregory has to scramble to put the pieces together before it's too late.
Where did the door come from? What was that creature? Can he save his sister, or is she already gone forever?