In an Italian household, siblings Io and Lei find themselves alone and bored. They decide to pass the time by masturbating in front of each other, a taboo act that sparks their curiosity and arousal. Io watches as Lei strokes her clit, her body writhing with pleasure, while Lei can't help but stare at Io's growing erection. They argue initially, but the tension is palpable, and soon they're both naked, Io's thick cock throbbing as Lei licks her lips, eager to taste it.