Shin Si-ah as girl (official name: 'Ark 1 Datum point'),Park Eun-bin as Kyung-hee,Seo Eun-soo as Jo-hyeon, a head office agent who goes out to get rid of the girl,Jin Goo as Yong-doo, the boss of an organization that disturbs the peaceful daily life of the siblings Kyung-hee and Dae-gil.,Sung Yoo-bin as Dae-gil, Kyung-hee's younger brother and 'girl's only friend.,Jo Min-su as Dr.Baek, Dr.Baek's twin sister,Kim So-min,Kim Ki-hae,Seo Yi-ra as Tou 4,Jung Ra-el,Justin John Harvey as new stealer working with Jo-hyeon.,Cha Soon-bae,Chae Won-bin as Tou 4,Special appearance,Kim Da-mi as Goo Ja-yoon,Lee Jong-suk as Jang, head of a secret research institute that pursues the whereabouts of the missing girl.,Uhm Tae-goo as Mart customers.
A girl wakes up in a gigantic secret laboratory. As the girl escapes from a laboratory, she stumbles upon Kyung Hee, who is trying to protect her house from criminal gangs. When the girl comes face to face with a criminal organization approaching Kyung Hee's house, the girl overpowers them with overwhelming power, and in the meantime, they start chasing her in the secret laboratory. Who is this mysterious girl and why is she being chased?