Onanigal delves into the darker depths of human desire, as a brother and sister grapple with their religious upbringing and the all-consuming lust that threatens to consume them. In the cramped closet, they struggle to maintain their virtue, but their bodies betray them, their semi-clothed forms pressed tightly together. As they succumb to their carnal urges, they are left to grapple with the consequences of their actions, their bodies slick with sweat and shame, their minds filled with the haunting echoes of their taboo lust.