When the island was bought by Rose Maxwell's family, they found a child, Beast of a Man, and they took him in at a young age. However, Rose resented both him and her parents for ruining their family. She murdered her parents and blamed the killings on him. Rose raised her infant brother, Cedric, making the "perfect" family in her eyes, knowing no one would believe Beast of a Man was innocent.
Many years later, Rose sees another threat to her perfect family when Lavinda becomes engaged to her brother Cedric. She plans a cunning plot to have the bachelorette party on the same island where her parents died, murder each of the ladies in turn, and once again blame the deaths on Beast of a Man.
She passes out during a fight with Julia and Emily while trying to murder them. She is then promptly arrested by the authorities. Rose only wanted to murder the members of the bachelorette party because they congratulated Lavinda for being engaged to Cedric.
Her unnamed father (chopped off head and stuck it on a pole)
Her unnamed mother (axed the body into two pieces)