Here, Aleks charts how the Web is forging a new brand of politics, both in democracies and authoritarian regimes. With contributions from Al Gore, Martha Lane Fox, Stephen Fry and Bill Gates, Aleks explores how interactive, unmediated sites like Twitter and YouTube have encouraged direct action and politicised young people in unprecedented numbers. Yet, at the same time, the Web's openness enables hardline states to spy and censor, and extremists to threaten with networks of hate and crippling cyber attacks.

'Just Do It: A Tale of Modern-day Outlaws' lifts the lid on climate activism and the daring troublemakers who have crossed the line to become modern-day outlaws. Documented over a year, Emily James' film follows these activists as they blockade factories, attack coal power stations and glue themselves to the trading floors of international banks despite the very real threat of arrest.

Hours before Mehmed II launches his final assault, an ominous sight shakes both sides. Rumors of a 40-ship fleet's imminent arrival have swirled for weeks, but it's exact whereabouts remained unknown. Ottoman cannons reduced the city walls to rubble, and Venetian reinforcements arrived too late. The conquest of Constantinople ushers in a new era for the Ottoman Empire, being a dominant force in world politics for 300 years. Mehmed II, in many senses, changed the nature of world history.

'The Coldest War': With the polar ice caps shrinking due to global warming, new trade routes are being exposed, along with billions of dollars' worth of natural-resource reserves. The five nations bordering the Arctic are readying themselves to fight for it. The problem is that there's one non-NATO country that already considers itself rightful owner of the region: Russia. With Vladimir Putin's recent military annexation of Crimea, there's a definite possibility its aggressions will boil over, returning the international community to precarious Cold War footing. We will head north to witness NATO forces participating in the largest polar military exercise in history. 'Heroin Warfare': Since the U.S. occupation of Afghanistan, heroin production in the region has skyrocketed, making the country the number-one producer by a large margin. Though Iran, Afghanistan's neighbor, is an ultraconservative country, Afghan heroin flowing across the border has actually caused Iran to have the worst heroin use problem in the world. Suroosh Alvi gets a rare look inside Iran to meet the suffering heroin addicts, and see how the country is coping with the illegal drug trade.

'Crude Awakening'- To combat the worst environmental disaster in American history, BP and the Coast Guard dumped nearly 2 million gallons of a chemical dispersant called Corexit into the Gulf. But instead of helping clean up the spill, Corexit made things worse. Shane Smith heads to Louisiana to report on the lasting effects of the BP oil spill. 'The Enemy of My Enemy' - Yemen, the fractured state in the Arabian peninsula, is at the top of the worry list for President Obama's national security team, and the rise of Al Qaeda there is only half the reason why. The real trouble is a current threat posed by the little-known Houthi rebel movement in the north of the country - a grassroots army, allegedly funded by Iran, that has never granted access to any other Western film crew before. Ben Anderson goes deep into Houthi-controlled territory to learn about the group that's fighting, and beating, Al Qaeda in the east, Saudi Arabia in the north, and Yemen's central government in the south.

Freeman's quest to understand what makes a rebellion successful brings him face-to-face with exiles, whistle blowers, hackers and movement leaders. From Berlin to Bolivia to the United States, he'll see the courage, dedication, hard work and hope that it takes to try to change the world.