Lucas' sister, a seemingly innocent girl, hides a secret life behind her WhatsApp. She's 'putinha,' a slut, for the men who send her explicit messages and videos. Lucas, unaware, stumbles upon her secret, catching her mid-self-pleasure, phone in hand. Intrigued and aroused, he delves into her phone, discovering a world of taboo desires. Their argument turns into a heated session, as Lucas, driven by curiosity and lust, gives in to the forbidden fruit, fucking his sister to the explicit messages that once belonged only to her.