Complex sentence: Norton and a small group of others (dubbed "The Flat Earth Society" by David) refuse to believe, and accusing David of lying, they venture out into the mist to seek help, where they are killed by a huge, unseen creature.
Split into simpler sentences: Norton and a small group of others refuse to believe, and are accusing David of lying. They venture out into the mist to seek help, where they are killed by a huge, unseen creature.