Tunnel

When mysterious murders involving only women occur, Detective Kwang-ho takes the case.

Kwang-ho finds himself 30 years in the future, and Korea's first female serial killer is found dead.

A fire erupts in the apartment below Kwang-ho, and Chief Sung-shik becomes suspiciuos.

A victim marked with the 7th dot appears as Seon-jae is desperate to catch the killer.

1958-born Kwang-ho chases 1988-born Kwang-ho to find his way back to his own time.

Seon-jae finds 1988-born Kwang-ho and begins an investigation to prove the other Kwang-ho is a fake.

Kwang-ho learns how fate has tied him and Seon-jae together, but Seon-jae is dubious.

Kwang-ho is shocked by his wife's death as Seon-jae suggests he catch the culprit with him.

The true culprit of the serial murders 30 years ago is revealed, and another victim appears.

Kwang-ho finally recognizes his daughter as he and Seon-jae work to arrest the suspect.

Ho-young commits suicide, and Kwang-ho finds new clues to the case from 30 years ago.

The real criminal behind the case from 30 years ago is revealed, and Kwang-ho returns to the past.

Kwang-ho finds the younger Jin-woo and chases him but is sent back to the present.

Jae-i tells Kwang-ho the location of the fountain pen, but Jin-woo is eavesdropping.

When Jin-woo decides to take revenge on Kwang-ho, Jae-i finds herself in danger once again.