Every night at 11:47 PM, Seo Yuna's phone rings — with a warning about tomorrow. The voice on the line is panicked, desperate... and it sounds exactly like her. She laughed off the first call. Then the last train proved it right. Now the phone is ringing again, and this time the voice tells her who it really is. A slow-burn mystery-thriller about warnings from tomorrow — and the price of ignoring them.