As the siblings huddle together in their closet, their bodies betray their strict upbringing. Their father's stern command echoes in their minds, "You mustn't move!" But as they struggle to remain still, their bodies respond to their taboo desires. The eldest sister's untouched vagina rubs against her brother's virgin cock, soaking it with her innate lubrication. They fall into a feverish rhythm, their bodies moving in unison, until they collapse into a heap of spent fluids and post-coital remorse, their minds filled with the shame of their sinful lust.