Mae Wilde yn ysu i ffitio mewn yn ei hysgol newydd. Ond mewn tywydd poeth ffyrnig, mewn ymarferion drama'r ysgol, sy'n adrodd chwedl leol o wrach o'r enw'r Gaeaf, mae'r wrach yn dechrau gadael llythyrau felltith brawychus i'r disgyblion. A all Wilde ddarganfod pwy sy'n ei wneud cyn i bawb ei beio hi?
Wilde is desperate to fit in at her new school. But in a fierce heatwave, in rehearsals for a school play telling the local legend of a witch called Winter, 'The Witch' starts leaving pupils frightening curse letters. Can Wilde find out who's doing it before everyone blames her? Or will she always be the outsider?
Eloise Williams grew up in Llantrisant and lives in West Wales, very close to the sea. Having studied Drama, she went on to work as an actor for over ten years before studying for a Masters in Creative Writing at Swansea University. She was chosen to be the first Children's Laureate Wales in September 2019. Wilde will be her fourth book with Firefly.