Lee, it turns out, is a master hypnotist. He had Dae-su conditioned during captivity. The “release” was staged. Every clue, every fight (including the legendary hammer-through-hallway scene—Dae-su takes on two dozen thugs with a claw hammer, one continuous shot of carnage), every meeting was choreographed.
She is not random. Lee arranged for her to work at that sushi bar, to be kind, to fall in love with Dae-su. Because Lee knows the final truth:
He doesn’t know she knows.
His captor releases him, dressed in a new suit, with a wallet, a cell phone, and a challenge: “Find out why you were imprisoned. You have five days. Fail, and someone else dies.”
The only human contact is the muffled sound of laughter from the TV—his own imprisonment broadcast as entertainment to his captor. On the news, he learns his wife has been murdered. He’s the prime suspect. Mi-do was adopted abroad.