Una pareja con problemas en su relación se muda al campo, donde descubren una cueva con una fuerza sobrenatural. Al beber agua de la cueva, comienzan a experimentar transformaciones físicas y emocionales que reflejan su codependencia.

Years into their relationship, Tim and Millie find themselves at a crossroads as they move to the country, abandoning all that is familiar in their lives except each other. With tensions already flaring, a nightmarish encounter with a mysterious, unnatural force threatens to corrupt their lives, their love, and their flesh.