A year has gone by since Eggsy Unwin (Taron Egerton) and the covert group Kingsman thwarted Richmond Valentine's nefarious plan involving neurological waves. Now, Eggsy embraces the mantle of Galahad, a title once held by his late mentor Harry Hart (Colin Firth), and enjoys life with Crown Princess Tilde (Hanna Alström) of Sweden. However, their normalcy is abruptly shattered when Eggsy is attacked by Charlie Hesketh (Edward Holcroft), a former Kingsman trainee left disfigured and mute from the last ordeal.
In a high-speed chase through London, Eggsy narrowly evades Charlie and his associates. Unbeknownst to him, Charlie’s severed cybernetic arm manages to breach Kingsman’s network through Eggsy's vehicle. Meanwhile, Lancelot (Sophie Cookson) uncovers a chilling truth: Charlie's cohorts all bear a golden circle tattoo, suggesting they belong to a criminal organization.
While Eggsy is away, disaster strikes as a series of missiles obliterate the Kingsman headquarters, decimating their ranks. As the last two standing, Eggsy and Merlin (Mark Strong) initiate the Doomsday protocol, which directs them to Statesman, a clandestine American agency masquerading as a bourbon distillery in Kentucky. There, they learn that Harry survived his injury but is now grappling with amnesia. They are briefed by Statesman’s chief, Champagne (Jeff Bridges), regarding a formidable terrorist coalition known as The Golden Circle.
Their quest begins with infiltrating the life of Charlie’s ex, Clara Von Gluckfberg (Poppy Delevingne). However, when Statesman agent Tequila (Channing Tatum) becomes ill, he is replaced by Whiskey (Pedro Pascal) as Eggsy’s partner. At the popular Glastonbury Festival, Eggsy successfully plants a tracker on Clara, but his revelation to Princess Tilde puts a strain on their relationship. After several failed attempts to restore Harry's memories, Eggsy finally breaks through by threatening a Cairn Terrier – a poignant reminder of Harry's deceased dog.
On the world stage, Poppy Adams (Julianne Moore), the nefarious head of the largest drug cartel and leader of The Golden Circle, broadcasts a sinister ultimatum: she has laced every recreational drug with a toxin, causing users to develop fatal symptoms. Demonstrating her power on a captured Elton John, she demands that the U.S. president (Bruce Greenwood) end the War on Drugs and grant her immunity. The President, realizing the potential benefits of this plan, pretends to cooperate while plotting to let the users die in quarantine, including his Chief of Staff, Fox ([Emily Watson]).
Driven by urgency, Eggsy, Harry, and Whiskey head to Italy to intercept the antidote after routing a call to Charlie from Clara. Though Eggsy successfully acquires a sample, chaos ensues when Whiskey inadvertently shatters it amidst an ambush. In a critical moment, Harry shoots Whiskey, suspecting betrayal; however, Eggsy uses a life-saving gel to help him.
Desperate, Princess Tilde reaches out to Eggsy in distress, revealing she has fallen victim to the toxin. With renewed resolve, Eggsy, Harry, and Merlin track down Poppy's hideout, dubbed Poppy Land, in Cambodia. Upon their arrival, Eggsy triggers a land mine, but Merlin heroically sacrifices himself to save the team. Charging into Poppy's lair, Eggsy confronts Charlie and ultimately defeats him, while Harry utilizes Elton’s support to combat Poppy's threat and her robotic guard dogs.
Armed with the antidote access code, Eggsy administers a lethal dose of Poppy’s own poison, persuading her to divulge the antidote's password before she succumbs to the very toxin she unleashed. Their mission takes a dark turn when Whiskey reveals his true motives, seeking to eradicate all drug users. In a climactic showdown, Eggsy and Harry confront and kill Whiskey, finally launching the antidote drones that will save countless lives worldwide.
In the ensuing aftermath, the President faces impeachment for his genocidal conspiracies against drug users, and Statesman announces plans to rebuild Kingsman with a new distillery in Scotland. To resolve the duplication of the Galahad title, Champagne names either Eggsy or Harry as Whiskey, but they both refuse. Stepping up, Ginger Ale (Halle Berry), the Statesman tech expert, fills the role. Ultimately, Eggsy and Princess Tilde tie the knot, while Tequila relocates to London to contribute to Kingsman’s mission.
