Keira Knightley risks it all to stand up to the British government — and stand up for the British people — in a new trailer for “Official Secrets.” Set in 2003, the political thriller is based on a true story and sees Government Communications Headquarters (GCHQ) translator Katharine Gun (Knightley) leaking classified information. She shares an email encouraging spying on members of the UN Security Council to force through the resolution to go to war with Iraq.

“I don’t collect information so the government can lie to the British people,” Katharine says in the spot. Despite being accused of betraying her country and threatened with a jail sentence, she refuses to back down. She’s told she has nothing to gain and everything to lose, but Katharine can’t bear to live in a world where powerful officials get to make up their own facts.

Knightley received Oscar nominations for “The Imitation Game” and “Pride & Prejudice.” Her recent credits include “The Nutcracker and the Four Realms,” “Colette,” and “Pirates of the Caribbean: Dead Men Tell No Tales.” Among her upcoming projects is Philippa Lowthorpe’s “Misbehaviour,” a comedy depicting the protest that disrupted the 1970 Miss World pageant in London.

“Official Secrets” made its world premiere at Sundance in January and hits select theaters August 30.