The Toronto International Film Festival, which opens in September, will showcase movies about the origins of WikiLeaks, the rise of Nelson Mandela, and slavery in America, organizers announced Tuesday. North America\'s largest film festival opens in six weeks, with fiction taking a backseat to movies about actual events. Bill Condon\'s \"The Fifth Estate,\" starring Benedict Cumberbatch as WikiLeaks founder Julian Assange will kick off the 38th edition of the festival. \"This dramatic thriller based on real events reveals the quest to expose the deceptions and corruptions of power that turned an Internet upstart into the 21st century\'s most fiercely debated organization,\" a statement said. The film chronicles the beginnings of WikiLeaks and asks \"the defining question of modern time: what are the costs of keeping secrets in a free society - and what are the costs of exposing them?\" The film also stars David Thewlis, Stanley Tucci, Laura Linney, Anthony Mackie and Dan Stevens. \"It\'s a film about what we believe is one of the most important issues of the day: information and who controls it,\" festival artistic director Cameron Bailey told a press conference. The film festival, which gets underway on September 5 and runs through September 15, showcases hundreds of feature and short films. It is the biggest film festival in North America and has traditionally been a key event for Oscar-conscious studios and distributors. This year marks the 25th anniversary of its MidnightMadness scary movies series, and organizers will be celebrating \"shock, horror and madness\" with a free screening of the slasher \"All the Boys Love Mandy Lane.\" Bailey also announced screenings for some 40 films by directors from South Africa, France, Canada, South Korea, Australia, Germany, the United States and Britain that he said \"capture the mood of the times.\" These include Justin Chadwick\'s \"Mandela: Long Walk to Freedom,\" based on the former South African president\'s autobiography chronicling his early life, coming of age, education, and 27 years in prison before working to rebuild his country\'s once-segregated society.The film stars Idris Elba as Nelson Mandela, and Naomie Harris as his wife Winnie Mandela. Jonathan Teplitzky meanwhile retells the epic true story of British Army officer Eric Lomax\'s confronting of a Japanese interpreter he holds responsible for his torture in a Japanese labor camp during World War II, in \"The Railway Man.\" It stars Academy Award winners Colin Firth and Nicole Kidman. Director Steve McQueen\'s \"12 Years A Slave,\" with Chiwetel Ejiofor, Michael Fassbender, Paul Dano, Paul Giamatti and Brad Pitt, looks back at the struggles of a free black man from upstate New York who was kidnapped and sold into slavery in 1841. Meanwhile, Julia Roberts and Meryl Streep team up for John Wells\' American Midwestern family drama \"August: Osage County.\" The movie, hailed by the festival as \"dark, hilarious and deeply touching,\" is based on Tracy Letts\'s Pulitzer Prize-winning 2007 play of the same name.