Murder in the Mystery Novel

From the back cover

After her sister Lily is found dead, Chloe is the only one in the family who grieves. Her parents, once cold and cruel, suddenly shower her with strawberry cake and old games, their kindness more frightening than their scorn. Then a timed message arrives from Lily's phone: she had discovered their secret, and the sentence breaks off unfinished.

Searching Lily's room, Chloe finds a diary. It tells of a man in black, of something red her father ate in the kitchen at night, and of a night when Lily looked through a keyhole and saw their parents' faces melting like wax. The final pages leave three rules to follow after midnight.

When footsteps stop outside the door, Chloe sees two pairs of black slippers standing side-by-side, toes pointing at her. She shuts her eyes and begins to count.