Realtor Jeong-tae (Byun Yo-han)'s hobby is sneaking into strangers' homes and peeping into their lives. One day, an unfamiliar face in the area grabs his attention - an Instagram star, So-ra (Shin Hye-sun). Miraculously, So-ra leaves her house key at Jeong-tae's agency and Jeong-tae visits her home whenever he can, thrilled and excited. Like any other day, Jeong-tae makes another visit and finds what he hadn't expected: the dead body of So-ra. Jeong-tae is shocked and he can't call the police and report. But when he returns few hours later with a client... So-ra's dead body is gone! Days later, Jeong-tae receives a red note saying 'It was you, right?'. Even worse, all evidences say that Jeong-tae is the criminal. Can he find the real killer and clear his name?