Young men and women have gathered again for the fourth season of "Heart Signal"; Yoon Jong Shin, Lee Sang Min, Kim Ea Na, Kang Seung Yoon, Mimi, and Kim Chong Ki join as panelists; someone's word turns the place into a battlefield.

The guys are busy on the weekend morning because of Ji Young; divided into three couples, the occupants spend the day together; the unexpected identities of the occupants are revealed; the old panelists show off their skills.

Objects are placed in front of the Signal House, arousing everyone's curiosity; the participants figure out that there will be a newcomer; Ju Mi is confused by how Ji Min and Min Kyu behave; Gyeo Re feels more distant from Ji Young.

The participants have their first dates; the ladies choose the gifts that men prepared without knowing whom they are from; Ju Mi wins in rock-paper-scissors and gets to go on a date with two male participants.

The ladies sit together and talk about their true feelings; they reveal whom they're drawn to and how their feelings have changed; after they return home, they decide to have a one-on-one talk with the guys of their choice.

A new female occupant joins the participants, and they have a welcoming party together; the appearance of a new occupant complicates feelings even more; Ji Min and Min Kyu have a secret date outside; Ji Won has the long-awaited date with Ji Young.