Pumpkin Night Chapter 25 -

"The sound of children’s laughter..." "Sound of laughter" could be Chorus of Giggles. For "trick-or-treated from house to house," synonyms might include Traveled Neighborhood for Treats.

Now, moving to the next sentence: "He told her about the ancient rituals that had been performed on this very night, and the terrible consequences that had befallen those who had participated." pumpkin night chapter 25

Breaking it down word by word:

So first sentence could be:

"that had befallen those who had participated" → "which had visited upon individuals who joined". "The sound of children’s laughter