Set in 1998 and 2023, 'A Time Called You' follows Han Jun-hee, a grieving woman who is still struggling with the loss of her boyfriend, Koo Yeon-jun, who died a year prior. Amidst her deep sorrow, she mysteriously receives a mysterious cassette tape that transports her back in time to the year 1998. Upon waking up in the past, Jun-hee finds herself inhabiting the body of a high school student named Kwon Min-ju. To her utter shock, she encounters a boy named Nam Si-heon, who bears an uncanny, identical resemblance to her late boyfriend, alongside his close friend Jung In-gyu. As Jun-hee navigates the complexities of teenage life in 1998, she races against time to unravel the mysterious connection between her current reality, the past, and a chilling murder case that threatens to alter history forever.