The trailer doesn't give too much away , but there is a plot synopsis that gives us a bit of context as to who the characters are and what's going on.
It reads:"High school student Sadie Harper and her younger sister Sawyer are reeling from the recent death of their mother and aren’t getting much support from their father, Will, a therapist who is dealing with his own pain."When a desperate patient unexpectedly shows up at their home seeking help, he leaves behind a terrifying supernatural entity that preys on families and feeds on the suffering of its victims.
It's not an exact adaptation of King's 1973 short story, but it's all about the scares anyway, and judging from the trailer, the final film should have plenty of those in store.