In the wildly overgrown garden of a New Orleans mansion, a family seeks the truth about the life and death of one of their own. After Sebastian Venable's mysterious death abroad, his mother Violet calls on her niece Catherine to reveal what happened that day. Catherine has been institutionalized since the death of her cousin for insisting upon a version of events so horrific that it can't possibly be true. Set on preserving Sebastian's memory, and erasing her own role in the unspeakable acts that led to his demise, Mrs. Venable will go to any length to discredit Catherine's account. But when Catherine is put under the influence of truth serum, everyone is forced to come to terms with the long-buried secrets that are finally brought to light.