Midnight

From the author of the horror classic Night of the Living Dead. 

Children can get away with murder under the cover of midnight...

Cynthia and her brothers had heard the stories about grandpa, who could summon demons and compel people to die with a curse. Maybe they also possessed the ancient powers. At first, they caught smallish demons who had assumed the shapes of rabbits and birds and then, larger ones like those who resembled the neighbor kids.

Now, they are growing, and their powers are swelling, nourished by adult desires. 

Soon, they will gather others like themselves from the earth's dark corners. Soon, they will begin the blood-drenched ceremonies performed one by one at midnight.