Episode 5 of Tempest kicks off with Mun-ju encountering Jun-ik's second family. The woman introduces herself as Kang Han-na, presenting her son, Eun-seong, as Jun-ik's nine-year-old boy. She divulges that both she and Eun-seong were present in the church on the fateful day Jun-ik was slain. Han-na discloses that she has undertaken a paternity test and intends to leverage it to challenge Jun-ik's will. Her ambition is to secure the inheritance for her son and further reveals that Ok-seon is backing her in this endeavor. She and Eun-seong are set to move into their residence soon. Han-na hurls insults at Mun-ju, questioning the authenticity of her grief given her composed demeanor and lack of tears. She vows to bring Mun-ju to tears.
Enraged, Mun-ju barges into Ok-seon's home to confront her. Ok-seon admits to having been aware of Han-na's existence from the outset. In fact, she suggests to Mun-ju that she could exploit this situation as a catalyst to garner more sympathy and ascend to the presidency. However, this is not the path Mun-ju wishes to tread. She tears up their contract and declares her intention to sever all ties with Ok-seon. When Ok-seon protests, Mun-ju unveils that she has amassed evidence of Ok-seon's long-standing tax evasion. She issues a stark warning to Ok-seon to silence Han-na.
Following this turn of events, Mun-ju requests San-ho to escort her to a secluded spot. He drives her out to the countryside, where she vents her frustration by firing at a target with his gun. As the day concludes, she expresses her gratitude to him.
Meanwhile, Im Du-jin conducts a public discourse on the US's impending assault on North Korea. He incites the youth to protest, but that very night, those same students turn violent against him. Mun-ju visits him in the hospital, where he imparts more crucial information - President Chae's meeting in China did not yield favorable results. He then enumerates the telltale signs indicating that the US is on the brink of launching an attack. One such sign is the airing of Frank Sinatra's rendition of "Have Yourself A Merry Christmas" on the radio, serving as a covert signal for citizens to evacuate. Just then, a group of suited men storms into the hospital and apprehends Du-jin on charges of espionage.
On another front, Mi-ji cracks the code to Jun-ik's encrypted email account by uncovering the password in his text messages. The correspondence between Jun-ik and John Cho unveils that three North Korean workers have defected to the US. Their testimonies describe North Korea's construction of a cutting-edge submarine. Subsequently, the government stumbles upon satellite imagery corroborating the submarine's existence.
Conveniently, fate played its cruel hand as one of the crew members turned on his comrades, killing the other two before taking his own life. Thus, John was left without the opportunity to interrogate them further. During his investigation, John uncovered a startling revelation: an American arms lobbyist by the name of Stella Young had been procuring the materials necessary for constructing a submarine. Yet, Stella had entered South Korea a decade prior and had remained there ever since. Jun-ik’s final email to John revealed that he knew who Stella was and was attempting to unravel the mystery.
Meanwhile, Mun-ju managed to secure a clandestine meeting with President Chae in a quiet church. She confronted Chae, demanding to know how she could have permitted the looming specter of war. Chae, with a somber expression, claimed she had been left with little choice. Undeterred, Mun-ju then sought out the Chinese ambassador, only to be met with a similar sense of resignation; even he insisted there was nothing that could be done to avert the impending conflict.
Gathering her team, Mun-ju journeyed to Busan for another public appearance. Seizing the moment, she bravely warned the crowd of the impending war and exposed President Chae's likely refuge in an underground bunker, while her citizens faced peril. Mun-ju laid bare all the details about the North Korean submarine and even brought Anderson Miller onto a video call. He testified that the United States lacked substantial evidence. Furthermore, he played a recording of a North Korean defector confessing that he had never actually seen the submarine, only heard rumors of its existence, and had been coerced into lying by his chief engineer.
By this juncture, special forces had surrounded the area, and chaos soon erupted. A sniper's bullet narrowly missed Mun-ju, but San-ho swiftly pulled her to safety, ushering her onto a boat. As they sped away, the sniper managed to graze Mun-ju's arm. San-ho guided her to a secure location to tend to her wound. There, she discovered he too had been shot, but with stoic resolve, he stitched her up before addressing his own injury.
Elsewhere, President Chae held a press conference, reassuring the populace that the United States would not take any drastic measures without first verifying the threat. She vowed to stand by her people and not seek refuge in hiding. A flashback revealed that Mun-ju had confided her plan to Chae in the church, proposing a partnership where Mun-ju would attempt to expose the Americans while Chae preserved her reputation.
At present, San-ho escorted Mun-ju to a safe haven. When her injury prevented her from washing her hair, San-ho gently stepped in to assist. Later, he taught her how to shoot with one arm. Over dinner, she opened up about her miscarriage, admitting to a tinge of jealousy towards Han-na—her son and the home adorned with cherished memories.
As they discussed the looming war, San-ho expressed a desire to be with his loved one when the time came. He then confessed that he wished to be by her side. Their lips met in a tender kiss, but the moment was abruptly shattered when the radio blared out "Have Yourself A Merry Christmas" on a US channel—a grim reminder that war was imminent. The South Korean government issued an urgent directive, instructing its citizens to prepare for evacuation.
