On a rainy day, Lee Min-kyung and Noh Hwi-oh experience a series of increasingly unpleasant encounters, unaware they live next door to each other.

Min-kyung is determined to find her missing dog. Getting wind of drug dealing activity on a chatting app, Hwi-oh sets out on an undercover mission.

At the police station, Min-kyung and Hwi-oh go at each other's throats. Later, Hwi-oh is advised to stay away from people who trigger his anger.

Bumping into an old coworker dredges up painful memories for Min-kyung. With a flasher on the loose, Hwi-oh is roped into patrolling the neighborhood.

Hwi-oh trains Min-kyung in the basics of self-defense. But soon, Min-kyung's anxiety returns in full force with the arrival of a sudden piece of mail.

Malicious rumors about Min-kyung spread online. While other neighbors turn against her, Hwi-oh promises she can always count on him to take her side.

The flasher resurfaces, this time in front of Min-kyung, but thankfully Hwi-oh is close by. The next day, she asks him for a favor.

A sudden incident in the night scares Min-kyung, who feels vulnerable living alone. Hwi-oh's mother discovers a woman in her son's apartment.

Min-kyung exchanges harsh words with her mother. She's further shaken by the identity of a prospective tenant who comes by to see her apartment.

As a show of repentance, the Women's Association sets out to help Min-kyung. After a night of drinking, Min-kyung tells Hwi-oh she wishes to see him.

After receiving good news at the psychiatrist's office, Hwi-oh heads to the police station. At the apartment, Min-kyung panics when her dog gets loose.

Hwi-oh's fury takes over when Min-kyung's ex-boyfriend shows up at the apartment. Lee Su-hyeon finds out that a video of her singing has gone viral.

Resolving to protect Hwi-oh, Min-kyung meets the one person she wanted to avoid. Concerned for her safety, Hwi-oh chases after her.