Following the events of the first film, a new semester unfolds at St. Trinian’s, where Annabelle Fritton [Talulah Riley] plays the role of the new Head Girl, steering the school through a fresh set of chaotic challenges and cheeky schemes. A new pupil arrives, Roxy [Sarah Harding], but she resists joining any of the familiar cliques—the Chavs/Rude Girls, the Emos, the Posh Totties, and the Geeks—while two new groups, the Flammables and the Ecos, loom on the social map, adding tension and curiosity to the corridors.
When Celia [Juno Temple], a member of the eco faction, is caught with an old ring in the Fritton Archives, a mysterious caller offers £20,000 for it, claiming the price will rise if she waits. The intrigue deepens as Annabelle pushes for more, demanding £100,000, but the voice on the line rejects the greed and threatens the girls. A power cut shatters the school’s routine, prompting them to seek help from Camilla Fritton [Rupert Everett], their headmistress and Camilla’s aunt, who quickly senses that the ring is no ordinary trinket. Camilla, a former pirate descendant herself, reveals that the ring is one half of a pair created by a pirate ancestor in 1589. When the two rings unite, they point to a buried treasure scattered across the globe.
Soon after, masked men led by Sir Piers Pomfrey [David Tennant]—a respectable figure who is himself a descendant of the man robbed by the pirate ancestor—launch a raid to seize the ring. The schoolies must act to protect the artifact and secure the second ring, which their archives hint at somewhere else. The team searches for the missing piece and uncovers a clue left by an earlier generation, directing them to a boys’ school. To recover the second ring, a portion of the group disguises themselves and infiltrates the rival institution, but the real challenge is understanding the intricate history behind AD1, a masculinist brotherhood led by Piers. Camilla enlists Geoffrey Thwaites [Colin Firth], the former head of education and a figure connected to Thwaites’ past, to help out, while Annabelle calls in Kelly [Gemma Arterton], now an M.I.7 agent, to coordinate the mission from behind the scenes.
Geoffrey, guided by Camilla’s insistence and a personal stake in the matter, goes undercover at AD1’s hideout. The group’s operation is delicate: they must retrieve the rings without triggering a larger conflict. The first ring is, in a tense moment, spotted on Piers and finally stolen back by Geoffrey, who delivers it to St. Trinian’s, restoring a glimmer of hope for the team. With both rings in hand, the cadets realize the coordinates engraved on them—longitudes and latitudes that point toward a very public treasure site: the Globe Theatre.
To outmaneuver AD1, the girls orchestrate a bold plan that hinges on a flash mob to divert attention. Camilla and Geoffrey, posing as actors they knocked out earlier in the manipulation, escort the team toward the theatre’s hidden heart. The treasure chamber within the Globe reveals a chest and a single note left by Pirate Fritton, explaining that the pirate eventually chose to abandon piracy and craft plays under the name of William Shakespeare. The treasure itself is not gold or gems, but the final play he wrote—a revelation meant to prove that Shakespeare was, in fact, a woman.
Piers tracks the party to the theatre, holds the group at gunpoint, and seizes the manuscript, triumphantly exposing that his ancestors predicted this truth and that he has long sought to confiscate it. He hopes to keep the revelation from the world, but the St. Trinian’s crew won’t yield so easily. They commandeer the reconstructed Golden Hind and chase Piers down the Thames, ramming his boat and reclaiming the script. Camilla recovers the manuscript from Piers, and the team carries the play back to the school.
Back at St. Trinian’s, the school parties in a raucous celebration of another hard-won victory. The fallout of Piers’ sexist agenda comes to light as the AD1 organization is dissected in the media, exposing him and his beliefs to public scrutiny. In a mix of wit, daring stunts, and a stubborn refusal to bow to patriarchal pretensions, the girls of St. Trinian’s prove that cunning, teamwork, and a little theatrical flair can overturn even the most entrenched obstacles. The semester ends with a sense of triumph tempered by the knowledge that the archive of their adventures is, in many ways, just beginning—and the legend of Shakespeare’s hidden gender history will ripple on through their school’s halls.
