When I woke up, I found that time had returned to yesterday. My time began to flow backwards day by day! Because of an accident, Eun-jo (played by Lee Cheong-e) lost her only happiness in life - her daughter. She fell into despair and made a major decision about her life, but when she opened her eyes again, time had returned to yesterday. Eun-jo, who began to flow backwards, changed her unfortunate yesterday little by little, but the time that kept flowing backwards also made her feel uneasy. On this day, she met Haomin (played by Hong Jong-hyun), a man who holds the key to this time journey... Can she turn back time and usher in a brand new tomorrow?