Season 1
Episode: 1x01 | Airdate: Jul 18, 2007
Soo Hyun bumps into Ji Woo and fall instantly in love with her, however little do both know that Ji Woo's Father and Soo Hyun's Mother are standing against each other with an outcome Soo Hyun never would expect.
Episode: 1x02 | Airdate: Jul 19, 2007
Min Gi and Soo Hyun are now both officially part of NIS. Min Gi falls in love with Ji Woo, while unaware that Soo Hyun and Ji Woo were childhood lovers.
Episode: 1x03 | Airdate: Jul 25, 2007
Deployed for his first mission of NIS, Soo Hyun bumps into someone which leads to some nasty consequences for him.
Episode: 1x04 | Airdate: Jul 26, 2007
Soo Hyun travels to Bangkok, Thailand to get his revenge for the death of his mother. Ji Woo surprises him and joins him, which is complicating Soo Hyun's task a lot.
Episode: 1x05 | Airdate: Aug 1, 2007
Hak Soo is giving Soo Hyun a chance to redeem himself as an infiltrant, however this action will hurt Min Gi, Ji Woo and family.
Episode: 1x06 | Airdate: Aug 2, 2007
Soo Hyun manages to infiltrate Cheong Bang as one of Mao's guys, while Ji Woo is struggling without him.
Episode: 1x07 | Airdate: Aug 8, 2007
Min Gi is telling his parents about an upcoming marriage. Soo Hyun manages to avoid a kidnap attempt of Ji Woo.
Episode: 1x08 | Airdate: Aug 9, 2007
Gumi Group catches Soo Hyun after miraculously surviving his injuries. After losing his memories, Mao comes up with a plan that surprises both his own and Gumi Group.
Episode: 1x09 | Airdate: Aug 15, 2007
Soo Hyun discovers that someone is wiretapping them and comes up with a plan to lure them out, however Joong Ho insists with Hak Soo to pull him out.
Episode: 1x10 | Airdate: Aug 16, 2007
Having made a deal with a company, Seo Young Gil is facing a nasty surprise which give him little to no choice to back out. While Cheongbang is out doing business, former Gumi Group leaders are plotting against them.
Episode: 1x11 | Airdate: Aug 23, 2007
Min Gi sets up an illegal team to defeat Soo Hyun and Cheongbang, but flips when Ji Woo is getting more involved with him. Soo Hyun continues to handle Ji Woo, while Oh Ming is very interested in him.
Episode: 1x12 | Airdate: Aug 23, 2007
Kay starts doubting himself whether he might have been a different person before his memory loss. During it's expansion into South Korea, a leak within gave the cheongbang a setback.
Episode: 1x13 | Airdate: Aug 29, 2007
Kay finally remembers his true identity and struggles to deal with it. Given a choice to remain Kay or to return to his old life, he is now forced to make a very important decision.
Episode: 1x14 | Airdate: Aug 30, 2007
Soo Hyun is in a difficult spot once he saves Min Gi and explains him about his true identity. Though the biggest challenge for both of them is Ji Woo.
Episode: 1x15 | Airdate: Sep 5, 2007
When Soo Hyun reports Cheongbang's plan to Chief Jung, Chief Jung orders the NIS with help of Byun Dong Suk to set out to retrieve information regarding the production plant of the drugs ''Balloon''.
Episode: 1x16 | Airdate: Sep 6, 2007
When both Soo Hyun and Mao are managing to escape the current situation, Soo Hyun manages to steal Mao's USB which has been given to the NIS. Mao, now sure that Soo Hyun is the traitor, is now out for vengeance, but both Soo Hyun and Mao end up with a nasty surprise.