Liam, an 18-year-old grappling with unrequited love decides he is going to eat a slug to impress a girl. He is interrupted by Mandy, a masked middle-aged woman who emerges from a rattling old fridge. Mandy claims to be Liam's wife from the future, urgently pleading with him to avoid eating a slug he found in the garden. Mandy reveals that the slug harbors a deadly parasite that will paralyze Liam for 17 years, derailing his life and leading to their eventual meeting in a rehab center. Despite his initial disbelief and mockery, Liam's curiosity and fear gradually give way to a reluctant acceptance of her bizarre story. Mandy's desperate bid to save Liam from a tragic fate culminates in a heartfelt connection. Her mission, however, also carries a poignant consequence: ensuring Liam's safety means erasing the future where they fall in love.

Sisters September and July share an intense bond, speaking in a secret language and keeping the outside world at a distance. After September is suspended from school, their mother brings them to a remote house on the Irish coast—where July begins to resist her sister’s increasingly sadistic control.