Shelly travels back to her hometown to help her estranged sister, Thelma, set up her wedding anniversary. Shelly thinks this will give the sisters something other than childhood abuse from their father to bond over. Shelly thinks Thelma and her husband, Trapper, have finally resolved their own volatile relationship after all these years. But when Shelly arrives, she discovers her brother-in-law chained up in a bathtub and her sister declaring that Shelly’s going to help her boil him alive.