Good Sister, Bad Sister: A BRAND NEW twisty, psychological thriller from Jill Childs for 2026

When Arabella discovers she was adopted, her stable life begins to unravel. She becomes obsessed with finding her birth mother and learning about an unknown twin sister. Helen, who has relocated to a quiet Cornish town, meets Arabella by chance. The two women form an immediate connection and begin supporting each other. When Arabella's mental state deteriorates, Helen becomes increasingly involved in her home and family life. As troubling events occur, Helen starts to question what she knows: Arabella's unexplained illness, her charming husband's true nature, and the secrets hidden within their household. By the time Helen discovers the truth, circumstances may have become irreversible. The novel explores themes of sisterhood, obsession, and the lengths people will go to alter their past.