Polly lives alone in a quiet, shadowy suburban home. Estranged from her family and nursing deep emotional scars, she spends her evenings in lonely routine. On a bitterly cold evening, an eccentric elderly woman knocks on Polly's door claiming her car has broken down. Despite initial hesitation, Polly feels pity and lets the stranger inside. Instead of calling for roadside assistance, the strange woman presents Polly with an ornate, hand-carved wooden box and an antique hourglass. Before vanishing into the night, the woman whispers a chilling warning: Polly has entered a game of survival. When the hourglass is turned, she must place three distinct items into the box before the final grain of sand drops: something she needs, something she hates, and something she loves. If she fails, an ancient malevolent entity will claim her soul. Panic sets in as the hourglass activates on its own. Polly attempts to leave the house, but every door and window is supernaturally sealed shut. Phone lines buzz with demonic static, and cellular signals cut out. In the pitch-black hallways, shadowy apparitions begin to stalk her. The entity takes on the physical appearance and voices of Polly's estranged mother Shannon, her sister Lydia, and childhood figures, mocking her past failures and dredging up buried family secrets. As the sand drains rapidly, Polly is forced to make desperate physical and emotional offerings. For something she needs, she offers her own blood and vital emergency medicine, slicing her palm over the velvet interior of the box. For something she hates, she burns treasured family heirlooms and letters of apology that caused her years of pain. But the third demand—something she loves—pushes Polly to the brink of insanity. Hallucinations blur the boundary between memory and reality. The entity traps Polly in an endless loop of her worst childhood memories, demanding the ultimate sacrifice. Polly realizes the elderly stranger who visited her was not a random witch, but a previous victim who had escaped the curse by tricking Polly into taking possession of the box. In a desperate, blood-soaked climax, Polly faces the faceless entity in the center of her living room just as the final grains of sand slip through the hourglass. Choosing survival over sentimentality, Polly makes the final sacrifice by surrendering her most deeply cherished memory and the talisman representing her sister. The house falls dead silent. The sun rises over the neighborhood. Polly steps out onto the front porch, alive, but permanently broken.

The ending of Vicious reveals that the wooden box is an ancient parasitic curse designed to perpetuate human misery. It cannot be destroyed, buried, or ignored. It demands three human sacrifices of increasing emotional severity to sustain its dark appetite. The elderly woman in the opening scene survived her own trial by passing the box to Polly. By offering something she needed, hated, and loved, Polly satisfied the immediate hunger of the entity and survived the night. However, surviving does not mean freedom. The entity has hollowed out her spirit, stripping away the grief, memories, and love that made her human. As Polly watches the sunrise, she hears a faint ticking sound behind her. The box sits on her porch table, its hourglass reset. Polly understands the cruel truth of the title: the cycle is vicious. She is now the new bearer of the curse, condemned to wander until she passes the box to another innocent soul, ensuring the nightmare never ends.