The story is simple yet beautiful. The most attractive part is the friend, It's remind me of my school days. Of course, it is hacking movie but it's not all about hacking, it's about friendship,college/school days moments. Unlike hacking movie,it is really funny.

However,the ending is totally unexpected. I really don't want to spoil it. I was expecting some kind of bomb that going to explode at the end but it isn't. I rather found it lame.

Twenty Hacker tells the tale of Jae-Min, who lost his father after some hackers use ransomware to attack his company's servers. For taking revenge, he keeps telling himself,''To protect your house from thieves,you must think like a thief and to catch a hacker,I must become a hacker'' and puts his all energy to become a hacker. Eventually he developed an extraordinary white hacking skill.

Despite that Jae-Min seems having perfectly normal life such as going to school, doing part time job, hanging out with his only one best friend named Jo-Hae. Nobody knows about his hacking skill except for himself.

Somehow, Jae-Min soon catch the eye of Cho's who also practices white hacking and run ''Better World'' group for helping others from cyber attacks. As the ''Better World'' group members become his friends, he involves them in his revenge plan and tells them to help him to find out his father's culprit.

Meanwhile,he along with other group members stopped scam schemes from happening including his best friend father from getting robbed. They are getting better together and racing against black haking.

Will Jae-Min able to catch the hacker whom he is been looking for years?