Forgotten - Ending Explained

The central twist of Forgotten is that the protagonist, Jin-seok, is not a 21-year-old living in 1997, but a 41-year-old man in 2017 suffering from dissociative amnesia. His 'family' are actors hired by the man pretending to be his brother, Yoo-seok. This man is actually Choi Seung-uk, the son of a family murdered in 1997, and the entire setup is a psychological play to make Jin-seok remember and confess to the crime.

Through flashbacks, the full tragedy is revealed. In 1997, Jin-seok's parents were killed in a car accident that left his real brother, Yoo-seok, critically injured. Driven by desperation due to the Asian Financial Crisis, Jin-seok accepted an online offer to kill a woman for money to pay for his brother's surgery. The offer came from the woman's own husband, a doctor, who wanted the insurance money. During the act, Jin-seok panicked and also accidentally killed the daughter but spared the young son (Choi Seung-uk). When confronting the doctor, a struggle ensued, and the doctor fell to his death. The trauma of these events caused Jin-seok to lose his memory of the past 20 years.

In the present day, after his memory is violently restored, Jin-seok is consumed by guilt. In a final confrontation, Choi Seung-uk asks if his father was behind the hit. To spare him that final, painful truth, Jin-seok lies and takes full responsibility. He then kills himself with poison. Having fulfilled his life's purpose and seeing no future, a weary Choi Seung-uk also commits suicide by jumping from the hospital window, ending the tragic cycle.

The most discussed area for alternative interpretation is the film's final scene. After the dual suicides, the film flashes back to 1997, showing a young, happy Jin-seok by a river just before his family's car accident. He has a brief, pleasant encounter with a little boy, who is revealed to be the doctor's son (the future fake Yoo-seok) with his family, all happy and alive.

One interpretation sees this scene as simply the last happy memory Jin-seok has before his life is irrevocably destroyed, a final moment of tragic irony showing him crossing paths with the very people whose lives he will later ruin.

Another reading views it as a poignant 'what if' scenario, a glimpse into an alternate reality where tragedy didn't strike, highlighting the cruel role of fate. It emphasizes that these were two separate, happy families whose paths crossed by chance with devastating consequences. A darker interpretation suggests that fate is inescapable; their meeting was not a coincidence but a precursor to an inevitable, intertwined doom.