Gu Jeong-tae is a real estate agent with a hobby of peeping into other people's lives by entering their homes using keys entrusted to him by customers. He becomes interested in and begins to observe Han So-ra, a social media influencer who posts photos of vegan salads while eating convenience store sausages. One day, Jeong-tae found So-ra lying dead on her sofa when he visited her house. Soon after, someone who knows that he entered So-ra's house starts threatening him. To make matters worse, Oh Young-joo, a homicide detective, starts an investigation with all evidence pointing to Jeong-tae as the criminal. Jeong-tae searches for people around him through So-ra's SNS to find the real culprit.