Encounter darkness

She knew her husband and her came from different worlds and believed their steadfast love would see them through. Her husband was fine, but it was his family that she needed to get used to; her brothers-in-law were odd and her mother-in-law was pleasant but somehow never the mother figure she thought she would be. As a visitor in their grand home with a rich history, she was perplexed to find that there were mysteries beckoning behind closed doors - who was the invalid, and why had there been deaths since her arrival? She did not know that she had encountered darkness until the riveting conclusion.