Two elite National Security System (NSS) agents, Hyung Jun and Sa Woo who were sworn blood brothers, both fall for fellow agent Seung Hee. Sa Woo attempts to suppress his feelings for Seung Hee and wishes the couple the best.
While Hyun Joon has been ordered to eliminate a North Korean figure in present day, we follow him and his budy Sa Woo back in time during their study and army training in which they both fall in love with a lady.
A nasty surprise is waiting for Hyun Joon and Sa Woo when they both accept the offer made by Baek San to join NSS. They are assigned to their first mission when a Japanese terrorist enters South Korean's soil.
Hyun Joon and Seung Hee are heading to Akita, Japan to spend their holiday together. The existence of NSS is in question, while code orange is in set in order to save Hong Seung Ryong.
Seung Hee worries about Hyun Jun when he is being assigned to a solo mission. Baek San orders Hyun Jun to assassinate an important North Korean figure.
Hyun Jun has been declared a traitor and is being hunted by both the NSS and the North Koreans. Trying to flee the country, Seung Hee is convinced of his innocence and tries to help him.
Hyun Joon is involved in a plane crash and is assumed to be death by NSS. Chul Young is giving Sun Hwa her final chance to locate and kill Hyun Joon, while Sueng Hee does not give up looking for him as well.
Hyun Jun has been imprisoned and has been given a chance to earn his freedom by performing a task. Seung Hee follows Sun Hwa in order to track down Hyun Jun. President Myung Ho sends over a North Korean delegation without negotiating with his allies.
Baek San orders Sa Woo to find a way to return Seung Hee to her former position. After a tragic loss, Hyun Jun discovers a secret organization called IRIS and plans to meet up with Chul Young. Sa Woo receives a disturbing video.
Hyun Jun joins the North Koreans in order to revenge South Korea's betrayal of him. Seung Hee officially returns to NSS. Sa Woo heads out to Pusan after a warning.
Hyun Jun hears about the actual target of the North Koreans and grabs his chance to collect data from Baek San's storage room. The NSS heads out to a thread, while unaware of the actual thread that's about to happen.
Hyun Jun finally discovers that Seung Hee is still alive. He escapes, with the terrorists, from NSS with a piece to a nuclear weapon. Now Hyun Jun has gained Park Chul Young's trust.
Hyun Jun makes contact with the secret man that saved his life in Hungary, in order to find out more about IRIS and his parents. Seung Hee has become obsessed, once again, with finding Hyun Jun, which is getting her in trouble with the NSS.
Seung Hee and Hyun Jun are reunited. But the terrorists force Hyun Jun to interrogate her for information. Meanwhile, it has finally been informed to everyone that the terrorists plan to use the nuclear bomb in Seoul during the reunification meeting of the North and South.
Park Sang Hyun and Seung Hee are beginning to suspect Sa Woo and Baek San of being traitors. Park Chul Yung is starting to have second thoughts about the nuclear attack. Meanwhile, Hyun Jun informs the South Korean President about IRIS.
Park Chul Young joins Hyun Jun and an unknown organization to stop the terrorist attack on Seoul. But first, they must track down the bomb. Meanwhile, IRIS is beginning to take control of the NSS.
The President has ordered Eun Gi Hoon's arrest. But when he turns up dead, the President orders Sa Woo and Baek San's arrests. Meanwhile, HyunJun, Sun Hwa, and Chul Young try to locate the nuclear bomb before it goes off at 5pm.
The terrorist attack has been stopped and the future is looking bright. Baek San and SaWoo are locked up and HyunJun and Seung Hee are back together. Now, it's time to find the people of IRIS who were not on the list.
Information has leaked out at NSS about the whereabouts of Baek San and Sa Woo. Yang Mi Jung has turned up dead. IRIS is planning an attack on the South Korean President. And Sun Hwa believes the Seung Hee may be an IRIS target as well.
Hyun Jun has found the IRIS base and arrests Baek San, but Sa Woo is still missing. The NSS tries to find out where IRIS' next attack will be. Meanwhile, Hyun Jun finds clues that lead to the belief that Seung Hee is not a target of IRIS, but another agent.
Hyun Jun and the NSS are able to save the hostages, but with the cost of Sa Woo's life. But on the night of the summit, the NSS receives word that the hostages were actually IRIS soldiers in disguise.
Yoo Gun has been requested to join NSS, while Choi Min has been appointed as new director of NSS solely to hunt down IRIS. Under command by Ray, IRIS leads a mission in order to retrieve Baek San.
When Yoo Gun barely escapes together with Baek San, it seems the NSS has still a mole within their organization. To repay his debt, Baek San warns Yoo Gun that IRIS will do something big during the talks between North and South Korea in Budapest.
When the North Korean spokesman has been assasinated by IRIS, Both teams of Yoo Gun and Chul Young are hunting down the killers. Unaware of the fact that the South Korean spokesman is without protection.
After failing to protect Jo Myung Ho, Yoo Gun has been sent off for a month as punishment and comes face to face with Ray. Deputy Director Choi Min orders Hyun Woo to catch Joong Won in Cambodia.
In order to find the culprit within the NSS, Yoo Gun creates a decoy of Baek San to lure them out. Baek San tells Choi Min the reason IRIS wants him so badly.
Yoo Gun has been kidnapped by IRIS in a very critical stage of health and this is tough for Soo Yun to handle. NSS finds it hidden mole and Choi Min officially declares war against IRIS.
The NSS is alerted when Chul Young is spotted with a team using false passports. Though Soo Yun spots an unknown man escorting Chul Young out on camera and has a feeling that it may be Yoo Gun. Yoo Gun is slowly starting to memorize some fights from before.
IRIS is planning an attack during the talks between both Korea's, while Yoo Gun is kept in dark by Rey. Yoo Gun slowly starts to ask more questions as part of his memories are returning. Soo Yun finds an hide-out of IRIS, while Joong Won raises ranks.
Together with Yoo Gun, IRIS infiltrates and to counter the talks between North and South Korea. A massive manhunt is initiated by NSS.
Yoo Gun is recovering his lost memories and realizes that he was originally not part of IRIS. Rie is ordered by Ray to kill him. While the NSS is forced to emergency state by North Korea's ultimatum.
Yoo Gun has been captured once again by IRIS as exchange item for Baek San.
The exchange between Yoo Gun and Baek Saen does not go as planned for both sides. Baek San manages to escape, while Yoo Gun has been granted his freedom.
In an attempt to eliminate Baek San, an unexpected casualty occurs instead.
IRIS and the NSS go head to head in a joint hostage situation. Yoo Gun secretly joins the fight for his own reasons.
Blinded by revenge, Yoo Gun resorts to torture. Meanwhile, IRIS's next mole in the NSS slowly begins to sabotage their operations.
Now that the nuclear weapons are in the NSS's custody, there are debates on whether to use them for power or destroy them to maintain peace with their ally countries.
Baek San tries to convince Yoo Gun to give up on his revenge against Joong Won before he and the people closest to him suffer.
Hyun Woo has a hard time forgiving Soo Yun for suspecting him as a traitor. Choi Min secretly plans to hand over the nuclear weapons to the U.S. Army.
Hyun Woo has a hard time forgiving Soo Yun for suspecting him as a traitor. Choi Min secretly plans to hand over the nuclear weapons to the U.S. Army.
With the means of a nuclear bomb, Yoo Joong Won takes his final stand in an attempt to start a unification war.
Complete episode guide for IRIS with detailed information about every season and episode including air dates, summaries, ratings, and streaming availability in United States.
This episode guide is organized by seasons, making it easy to track your viewing progress or find specific episodes. Use the episode information to plan your binge-watching sessions or catch up on missed episodes.