Episode 4 of Snowdrop opens as Soo-ho returns to Yeong-ro and gifts her his pigeon necklace. In the overlooking café, Seol-hui realizes that Gwang-tae called the ANSP and runs down to warn Yeong-ro. They send Soo-ho on his way and act oblivious when Gang-mu appears.
Gang-mu takes Gwang-tae back to the ANSP headquarters to interrogate him, distrustful since Gwang-tae’s call came at the same time the agents were searching Mount Ogong (which borders the dorm) for the dead drop used by the North Korean spies. Even as the questioning gets physical, Gwang-tae is determined to win Seol-hui over by maintaining that he simply made a mistake.
Soo-ho makes his way to Taeguk Hardware Store – the front for his spy base – and learns of Geum-cheol’s suicide. Comrade Joo eyes Soo-ho with suspicion and we flash back to Soo-ryeon giving Comrade Joo the order to kill Soo-ho if he senses Soo-ho’s ideology wavering.
Bun-ok accuses Yeong-ro of flaunting Soo-ho around the dorm to spite her. Returning to her desk, Bun-ok racks her mind but cannot remember letting Soo-ho in through the ticketing station. When the record from the open house confirms this, Bun-ok becomes sure that Soo-ho was the spy in the cabin.
In 207, after Yeong-ro recounts her confrontation with Bun-ok, Jeong-min fears that Bun-ok will catch onto them. They decide they need to hide the backpack full of Soo-ho’s bloodstained clothes.
After the lights go out, Man-dong makes a sneaky phone call to his son, who is so deep into a loan that he has now put his organs down as collateral.
Yeong-ro sneaks through the hallways wearing the backpack, unaware that Bun-ok is creeping along behind her. She finds Man-dong as he’s putting the phone away and asks him to store the backpack in his room. Bun-ok watches them from the shadows.
The following day at the ANSP headquarters, Ha-na comes to Gang-mu’s office with an orchid plant for his desk. She tells Gang-mu that she only joined the ANSP to ask the man who proposed to her and then vanished why he left her. Stone cold, Gang-mu says that he’ll pretend he didn’t hear her and starts to leave. Ha-na begins to ask him why he left her but thinks better of it. Instead, she tells him that he cannot trust the agents on his team to stay loyal to him while he’s disobeying direct orders. She will tail Professor Han herself.
Bun-ok calls the ANSP, asking if the reward for information on those harbouring a spy is as high as the one for information on the spy themselves. The matron catches her celebrating that it is and cuts the call.
Bun-ok accuses the 207 girls of harbouring Soo-ho and takes the matron to Man-dong’s room to find the backpack. After uncovering it, the matron tells Man-dong that he will soon be relieved of his position.
The matron has Bun-ok collect the backpack and bring it to her office. Once there, the matron stresses the danger the whole dorm will be subjected to if Bun-ok tries to turn the 207 girls in. The matron says that Bun-ok, the younger sister of a communist, would be an easy target for the ANSP to frame as a spy. The matron also mentions that Bun-ok’s sister jeopardized her family’s position to the point where factories won’t even hire Bun-ok. Apparently the only reason that the matron did was because of her loyalty to her old teacher.
Next to file into the matron’s office are the 207 girls, already one strike away from getting kicked out. Yeong-ro takes the fall for the whole group, insisting on her knees that she hid Soo-ho against the other girls’ wishes. She’s given until the following day to leave the dorm and the rest of the girls are banned from receiving callers.
At his base, Soo-ho phones Ji-rok to say that his wound has healed and he’s ready for his mission. Their conversation reveals that Ji-rok is Soo-ho’s father and that Soo-ho’s real name is Soo-hyeok. Soo-ho is also Ji-rok’s last hope against an ousting.
Ending the call, Ji-rok tells Soo-ryeon that Soo-ho will complete the mission. She interjects with the news that she sent in a new team. Ji-rok insists that Soo-ho will lead them and orders Soo-ryeon to stay out of further South–North negotiations.
That night, over dinner with Tae-il and Chang-su, Ji-rok raises the price of his cooperation to $400M. When Chang-su is unwilling to bleed Aemin Party dry, Tae-il reveals the ANSP’s secret fund, which has been kept from both the President and the Assembly and doesn’t require receipts.
The next day at a church, Ha-na observes Professor Han going into the confessional. On the other side of the partition, Soo-ho sits disguised as a priest and points his gun at Professor Han. Soo-ho claims that Professor Han’s son went willingly to Pyongyang with him six months ago and he’s got pictures of the son smiling in the city as proof. Soo-ho also says that the CIA will soon discover the son’s defection and then it’s only a matter of time before the ANSP does too.
Leaving the church, Professor Han hails a taxi without realizing that its driver is Comrade Joo. Ha-na drives after them but a ruckus on the road caused by the newly arrived North Korean spies halts her chase.
Comrade Joo take Professor Han to their headquarters to read a letter penned by his son. Soo-ho interprets the letter’s vague wording, explaining that life in Pyongyang isn’t easy for outsiders and the professor’s son has been trying to escape. According to Soo-ho, the only way for the professor’s son to escape is if the professor goes to the North to get him. The professor acquiesces and Soo-ho leaves him blindfolded in their backroom to wait.
Gathering his forces, Soo-ho orders them to travel ahead with Professor Han to the port where their boat will be waiting at 10pm to take them home.
Meanwhile, Gang-mu deciphers one of Soo-ho’s coded messages and learns that he had been hiding at the dorm. Jumping into action, he heads to the dorm and sends Ha-na to Mount Ogong.
Parting from his team, Soo-ho detours to Mount Ogong to retrieve the weapons and money hidden in their dead drop. After finding it, Soo-ho turns back and sees a paper plane wedged into the fence bordering the dorm. He unfolds it to reveal a message from Yeong-ro expressing her disappointment at his lack of contact.
In the dorm, a goodbye part for Yeong-ro is underway. All the girls do their best to keep the mood cheerful until Seol-hui can’t hold her tears in any longer.
Man-dong’s wayward son approaches Soo-ho by the fence, thinking Soo-ho is a pervert spying on the girls. Soo-ho spots the ANSP team led by Ha-na getting closer and flees. Man-dong’s son thinks that they’re after him because of his debt and follows.
The two end up going into the hut that shelters the secret passage to the mechanical room in the dorm. By the time Ha-na looks inside, they’ve already gone into the passageway and covered its entrance. Man-dong’s son starts getting aggressive and pulls out a knife. Soo-ho pins him to the floor as Man-dong himself comes up the passageway with a mallet.
Seol-hui waits outside the dorm. She watches with disappointment as Byeong-tae arrives, having been called by Hye-ryeong to help Yeong-ro move out. Her feelings turn to elation when Gwang-tae also arrives, just released from the ANSP headquarters and sporting bruises across his face. He tells Seol-hui that he endured torture without spilling her secrets and she’s moved.
Gwang-tae notices Gang-mu pulling up to the dorm and bolts inside with Seol-hui, discarding the tissue he was using to sell his sob story onto the bonnet of Byeong-tae’s car. Furious, Byeong-tae chases after him.
Gang-mu doesn’t even spare them a second glance as he enters the dorm and begins another search. He eventually makes his way down to the mechanical room and is attacked by Soo-ho. Soo-ho incapacitates Gang-mu long enough to run into the foyer unhindered.
Once there, Soo-ho finds himself surrounded by ANSP agents with their guns ready. Yeong-ro comes down the stairs and is stunned to see Soo-ho. Gang-mu rushes into the foyer to join his agents at the same time Ha-na’s team does.
Soo-ho cages Yeong-ro against himself and raises his gun to her head, telling the agents to drop their guns. He fires a warning shot at the roof when they don’t comply and gives them until the count of three or Yeong-ro’s life is forfeit.
He counts all the way to three and a gunshot resounds…