Star Keira Knightley has become synonymous with period dramas. From 2005’s PRIDE & PREJUDICE to this year’s THE AFTERMATH, she has shined in the genre. But Knightley takes a bold turn in her new political drama, OFFICIAL SECRETS, in which she plays a British intelligence specialist who risks everything to stop an unjust war.

Katharine Gun (Knightley) routinely handles classified information, but she’s shaken by an NSA memo she receives one day in 2003: The United States is enlisting Britain’s help in spying on United Nations Security Council members in order to blackmail them into voting in favor of an invasion of Iraq.

Shocking, right? Did we mention OFFICIAL SECRETS is based on a true story?

Now Gun faces a gut-wrenching decision: Does she do her job and keep her head down, or does she speak up? Unable to idly stand by and watch the world be rushed into an illegal war, Gun ultimately leaks the memo to the press, setting off an explosive chain of events that will ignite an international firestorm, expose a vast political conspiracy, and put Gun and her family directly in harm’s way.

It’s no spoiler that despite Gun’s actions, the Iraq War still happened, but Gun has no regrets about telling the truth. In an interview with Vanity Fair, Gun said she hopes her story in OFFICIAL SECRETS will help inspire others to speak up for what’s right. “In any walk of life, you can choose to do the right thing,” she said. “At the end of the day, we are accountable to our conscience. We should think about that and remember that.”

OFFICIAL SECRETS opens in limited release this weekend and expands in the coming weeks. Find showtimes and get tickets at an AMC near you.