When the Phone Rings ending explained: who the kidnapper really is

MBC's When the Phone Rings wrapped its 12-episode run on January 4, 2025, with an 8.6% nationwide rating for the finale, per Nielsen Korea, and became a Netflix hit along the way, peaking at 6.6 million weekly views. Yoo Yeon-seok plays Baek Sa-eon, the youngest presidential spokesperson in the country, and Chae Soo-bin plays Hong Hee-joo, the sign language interpreter he married in an arranged match. They've barely spoken in three years. Then someone kidnaps her, and the calls start.

TIME's Kayti Burt called it "one of the best makjang dramas we've gotten in a few years," and makjang is the key word. Spoilers from here.

The kidnapper is the real Baek Sa-eon

The man making the calls (Park Jae-yoon) is the real Baek Sa-eon, the biological son of presidential candidate Baek Ui-yong. The man Hee-joo married isn't.

The setup goes back decades:

• The swap: Grandfather Paik Jang-ho tried to drown his grandson as a child. A fisherman, Jung Sang-hoon, raised the boy instead, and someone else grew up in his place as the family heir.
• The secret: The penultimate episode reveals who that heir really is. Sa-eon records Jang-ho's confession through a camera hidden in a signet ring and hands it to the police. The man Hee-joo married turns out to be Jang-ho's own son, which makes him the kidnapper's uncle.
• The motive: The real Sa-eon wants revenge on the man living his life, and he goes after Hee-joo because she's the thing that man cares about most.

He also had help on the inside. Episode 9 reveals that Park Do-jae (Choi Woo-jin), Sa-eon's closest aide, was assisting the kidnapper.

The Paik family wanted one perfect heir and ended up with two: one raised in a mansion, one raised by a fisherman.

What happens at the end

The family has more than one villain. Sa-eon's mother, Kyu-jin, has Hee-joo taken at the end of episode 10 and fakes her death. A family enforcer, Min Do-ki, is ordered to kill her and lets her go instead. Kyu-jin ends the series sentenced to life in prison, and Baek Ui-yong loses the presidential election.

Don't miss: Babylon Berlin ending explained: do Gereon and Charlotte make it out of 1933 Berlin together?

The real Sa-eon gets one more twist in before he goes down. As police close in, he whispers to the other Sa-eon that Jang-ho arranged the car accident that killed Hee-joo's brother. Sa-eon reaches Hee-joo before the kidnapper can shoot her.

Hee-joo and Sa-eon get their happy ending

Then the show does something unusual for a makjang finale: it lets its leads be healthy. Hee-joo and Sa-eon divorce and then remarry, this time for real, and he takes a new name, Paik Yu-yeon. Hee-joo sets boundaries with her mother and makes peace with her sister, In-a. Yu-yeon reconnects with Jung Sang-hoon, the fisherman who raised the boy he replaced, and goes back to hostage negotiation.

After 12 episodes of threatening phone calls, the last thing the show gives them is a marriage where they talk to each other, which is quite a finish for a couple whose first scene was three years of silence.

Previously we wrote: The Institute ending explained: Stephen King's book ends with the Institute exposed — the show doesn't