A young couple from Brooklyn, whose relationship is on shaky ground, decides to retreat to a secluded bed and breakfast to try and mend their issues. However, as soon as they step foot into The Happy House, they are met with a series of calamities, leading them to believe they might have stumbled into a real-life horror film. The situation quickly spirals from strange to terrifying as they deal with the eccentric owner of the house, her formidable son, a temperamental Swedish butterfly expert, a nitpicky English professor, an extremely rare butterfly, the most delicious blueberry muffins, a .44 Magnum, a deranged serial killer, and a very strict set of house rules.