In the climactic battle of the war, Matthew and William go over the top to an uncertain fate. Vera plays a cruel endgame with Bates and Anna. And Daisy faces the severest test of her life. Followed by Part 5: As the war nears its end, Downton's aristocrats and servants put their lives back together. Mary and Sir Richard go estate hunting. A mysterious wounded officer makes a shocking revelation.

This program tells the story of William Still, one of the most important yet unheralded individuals of the Underground Railroad. The film details the accounts of black abolitionists, who had everything at stake as they helped fugitives follow the North Star to Canada.

FREEDOM RIDERS: AMERICAN EXPERIENCE is the powerful harrowing and ultimately inspirational story of six months in 1961 that changed America forever. From May until November 1961, more than 400 black and white Americans risked their lives -- and many endured savage beatings and imprisonment -- for simply traveling together on buses and trains as they journeyed through the Deep South. Deliberately violating Jim Crow laws, the Freedom Riders met with bitter racism and mob violence along the way, sorely testing their belief in nonviolent activism.

Are we, in an effort to outwit raccoons, actually making them smarter and unwittingly contributing to their evolutionary success? Are the ever more complex obstacles that our fast-paced urban world throws at them actually pushing the development of raccoon brains? In this film, scientists from around the world share their thoughts and work to help explore this scientific theory. Attempting to do something that has never been done before, they closely follow a family of urban raccoons as they navigate the complex world of a big city.

This is the incredible story of Trishna and Krishna, twin girls born joined at the head. Abandoned shortly after birth at an orphanage in Bangladesh, they had little chance of survival, until they were saved and taken to Australia by an aid worker. After two years battling for life, the twins are ready for a series of delicate operations, which will prepare them for the ultimate challenge: a marathon separation surgery that will allow them to live truly separate lives. Surgeons knew there was no guarantee of survival for either of the girls -- but without surgery there was no hope at all.

The experts dissect a lion and a tiger. From the outside, the two look very different, but once their skins are removed, even the experts find it hard to tell them apart. Biologist Simon Watt comes face to face with a liger - a cross between a lion and a tiger - proof of the two species' similarity. One of the most characteristic features of these magnificent animals - something that distinguishes them from the small cats - is their ability to roar. The team delves into the lion's throat to find the voicebox and makes a discovery that helps explain the way the vocal apparatus works. Richard Dawkins explains the evolutionary arms race between predators and their prey in the struggle to survive.

DCI Barnaby returns from a holiday in France to discover an unidentified tramp has been beaten to death in the woods near the village of Marshwood. While Barnaby was away, Supt. Ronald Pringle, just before his retirement, quickly arrested a local young man. But Barnaby suspects that he is innocent, which is only reinforced when there is an apparent suicide at the same spot. He tries to uncover the connection before there can be a further murder.