Seo-yeon verblijft alleen in een groot huis waar ze steeds vaker wordt lastiggevallen door mysterieuze telefoontjes. Op een gegeven moment komt ze erachter dat ze belt met een meisje dat in hetzelfde huis heeft gewoond, maar dan twintig jaar geleden. Deze vrouw speelt met het leven van Seo-yeon om haar eigen lot te veranderen.
| Directing | Lee Chung-hyun | Director |
| Writing | Lee Chung-hyun | Writer |
| Production | Jeong Hui-sun | Producer |
| Writing | Kang Sun-ju | Writer |
| Production | Syd Lim | Executive Producer |
| Editing | Yang Jin-mo | Editor |
| Sound | Dalpalan | Original Music Composer |
| Camera | Cho Young-jik | Director of Photography |
| Art | Bae Jung-yoon | Production Design |
| Lighting | Jung Hae-ji | Lighting Director |
| Costume & Make-Up | An Ji-hyeon | Costume Design |
| Costume & Make-Up | Park Ye-ri | Makeup & Hair |
| Writing | Kim Hee-jin | Adaptation |
| Art | Oh Jin-seok | Props |
| Editing | Vanessa Taylor | Colorist |
| Production | Kim Woo-taek | Executive Producer |
| Sound | Park Yong-gi | Sound Supervisor |
| Writing | Sergio Casci | Original Story |
| Costume & Make-Up | Hwang Hyo-kyun | Special Effects Makeup Artist |
| Costume & Make-Up | Kwak Tae-yong | Special Effects Makeup Artist |
| Sound | Ahn Bok-nam | Production Sound Mixer |
| Visual Effects | Hong Jang-pyo | Special Effects Supervisor |
| Production | Jay Lee | Executive Producer |
| Art | Song Suk-ki | Set Decoration |
| Costume & Make-Up | Heo Jin | Costumer |
| Costume & Make-Up | Shin Soo-bin | Costumer |
| Costume & Make-Up | Yoon Na-yeon | Costumer |
| Camera | Lee Joong-wan | Key Grip |
| Sound | Yoo Seok-won | Sound Effects |
| Production | Jang Eun-young | Line Producer |
