Season 1

Aboard a falling plane as the clock ticks toward doom, Han Tae-sul puts his famous mind to work for a solution. Gang Seo-hae arrives in the year 2020.

The contents of a mysterious suitcase give Tae-sul more questions than answers. In exchange for lottery numbers, Sun agrees to help Seo-hae.

Tae-sul's presentation at a conference gets a violent interruption. He and Seo-hae make a narrow escape, but more trouble soon follows.

On the run from the enforcement agency, Tae-sul and Seo-hae give in to the time traveler's request that they make a stop at his mother's house.

Caught by Kim Seo-jin trespassing in her clinic, Tae-sul tries to explain what's going on. Seo-hae reveals disturbing details about the future.

Seo-hae infiltrates Eddy Kim's party with a mission. After a series of distressing events, Tae-sul realizes he cannot trust everyone around him.

Seo-hae urges Sun to flee the country, and asks Mr. Park to do her a favor in exchange for an item he's eager to get his hands on.

Despite Seo-hae's insistence that he lie low, Tae-sul focuses on tracking down an enigmatic figure who seems to be tied to everything.

At the amusement park with Tae-sul for her birthday, Seo-hae encounters someone unexpected. A familiar threat strikes again.

Tae-sul enters enemy quarters to retrieve Seo-hae. Learning she's been put in a dire condition, he turns to a grudging Mr. Park for assistance.

Tae-sul and Sigma come face-to-face. In order to rescue Seo-hae, Tae-sul must endure an emotional trip through his past.

When Seo-hae wakes up, a person she missed is waiting to meet her. A long-forgotten childhood memory returns to Tae-sul.

Tae-sul is reunited with a trusty friend, who comes to him with a warning. A suitcase containing disturbing contents arrives at Asia Mart.

With the war looming on the horizon, everyone must make their choices. When Seo-hae heads to the only place she knows, Tae-sul finds her.

As Tae-sul tries to locate him, Sigma reveals more details about himself. Sun frees Seo-hae from the bunker.

Tae-sul asks Seo-hae to trust him no matter what happens — and demonstrates that nothing is fixed when it comes to matters of the future.