Harry (Colin Firth) is a member of the British secret agent organization Kingsman. In an operation, his comrade unfortunately died. Harry handed a badge and a phone number to his comrade's young son Eggsy (Alex Nikolov), telling him to call this number if he encounters any trouble in the future. However, this opportunity can only be used once. In a blink of an eye, 17 years later, the broken family made Eggsy (Taron Egerton) grow up to be a gangster who has nothing to do all day. One day, Eggsy, who was arrested for violating traffic rules, used the precious number in his hand. Harry, who came, discovered his kind nature and high talent under Eggsy's cynical appearance. So, Harry decided to train Eggsy to become a new generation of Kingsman. What they need to face together is the powerful and evil billionaire Valentine (Samuel L. Jackson).