The storyline centers on Han Tae Sool (Cho Seung Woo), a genius engineer, and Kang So Hae (Park Shin Hye), a girl who is the most powerful warrior. They embark on a journey through time to discover the truth.
Han Tae Sul is the co-founder of Quantum and Time, known as a genius in engineering and coding. After the death of his older brother 10 years ago, Tae Sool’s strange behavior led to fluctuations in the company’s stock. One day, after witnessing the unbelievable truth of his brother’s death, he sets off on a dangerous journey.
Kang So Hae is an elite warrior who has all the skills needed to survive in a world overrun by gangsters and military dictators. From hand-to-hand combat to sniper rifle, from planting bombs to rappelling from high-rise buildings, she is excellent at everything. Seo Hae becomes Tae Sool’s protector on his dangerous journey.