Foliage and Fatality

Seventy-something sisters, Max and Lil, visit western Pennsylvania, partly to see Lil's son Terry and his family, and partly to enjoy to colorful fall foliage. The sisters volunteer to help staff a fund-raiser haunted house. The house has amazing special effects and a haunted garden. It is hugely popular and should bring in a lot of money for the new school auditorium. What could go wrong?