A young woman named Jay is in a blossoming relationship with a guy named Hugh when their date takes a terrifying turn. After an intimate encounter, Hugh reveals to Jay that he has passed on a supernatural entity to her through sex. This entity, invisible to everyone except the afflicted, relentlessly pursues its target at a slow, walking pace. If it catches and kills its victim, it reverts to the previous person in the chain. Desperate and terrified, Jay begins to see people following her everywhere she goes, some appearing as strangers, others taking the form of familiar faces. She initially panics, leading her friends to believe she is having a mental breakdown.

Jay confides in her close friends Paul, Yara, and Greg, who ultimately believe her after witnessing strange occurrences themselves. They band together to help find a way to stop or at least delay the relentless entity. The group attempts various strategies, including researching the origins of the curse and formulating plans to evade or confront the entity. Jay’s growing paranoia and fear drive her and her friends to their limits as they navigate the terrifying new reality that every step taken could mean life or death. Together, they face mounting challenges and make difficult decisions in their struggle for survival.