Sinister Things is a novel that follows Carolyn, who is trying to adjust to life as a single stepmother and as the queen of the Night Wisps. Her daughter, Hanna, is reluctant to live among the Night Wisps after what they did to her in the past but slowly comes to love them like family.

One night, while Carolyn is working, the Night Wisps murder an innocent man pulling a prank in order to protect their queen. This leads to an investigation, the arrival of three unknown dark creatures, and a struggle for Carolyn to hold on to all that she loves and cares about without losing her own humanity in the process, assuming she has any left over after the events in Stain.