In 2006, Joyce Vincent was found dead in her North London flat with her television still on and newly wrapped Christmas presents around her. She had been dead for three years. But who was she? Why didn't her family report her missing? How could someone just disappear like that? There was no way to determine the cause of death, because the body was so badly decomposed, although the police ruled out suspicious circumstances.

Clearly there's a lot more to this story than meets the eye. To piece together a timeline, Morley interviews journalists, council employees and Joyce's friends. Morley also inventively uses actors (Ashton and Luka-Cain play her as a woman and child) to re-enact scenes from Joyce's life based on photos showing a lively, educated, sexy mix-raced woman who wasn't even 40 when she died.

The camera work is sharp and intimate, and as the film progresses, Joyce's life begins to come into focus. Watching her friends react to a recording of her voice is moving, while the re-creations show a head-turning woman who was the life of the party but was secretly lonely. She drifted in and out of peoples' lives, adapted to them, got into an abusive relationship and eventually lost touch with her friends, who just assumed that she had moved on.

Despite feeling rather padded out, the film is a powerfully evocative exploration of how easy it is to get lost in a big city and how little we actually know about friends we assume are out there having a great life. Everyone has a past that we know very little about. Joyce certainly did, and as she moved around London over the years she always fitted in with the people she met, yet no one noticed it when she vanished. And as her story starts coming into focus, the film takes on a bluesy, sad tone that really gets under the skin.

Gene Sharp is an unassuming 83-year-old political science professor whose writings have changed global history. His specialty is peaceful resistance, and his books have been used to challenge oppressive governments everywhere from China to Zimbabwe, including in the Arab states this past spring. Basically, he distils common-sense ideas into practical actions like using an identifiable colour scheme (such as Iran's green protests), painting signs in English (to draw foreign pressure) and, above all, avoiding all violence while winning over the police and military to the democratic cause.

His one colleague in his Boston office is Raqib, an articulate and passionate former Afghan refugee. And then there's Helvey, an ex-military man who uses Sharp's theories to help revolutionaries all over the world. We also meet local protest organisers like Popovic in Serbia, Maher in Egypt, Viatrovych in Ukraine and Athanasiadis in Iran, all of whom have put Sharp's principles to use, with varying degrees of success.

The film is shot and edited with skill, drawing us into the story while carefully outlining the theories point by point. And along the way the most surprising thing is that Western governments have completely dismissed Sharp's writings. It's difficult not to conclude that they're actually not interested in democracy or freedom at all, but rather in how much money the military-industrial system can make. Which makes this film rather terrifying.

Through all of this, filmmaker Arrow recounts Sharp's life in a thoroughly involving way, highlighting his "eureka!" moments and weaving in astonishing footage from the front lines of each protest mentioned. These clips are rarely seen glimpses of people standing up for freedom in a peaceful way, often facing horrific violence at the hand of their own governments.

Seeing Sharp's massive impact on world history is thoroughly inspirational, mainly because he refuses to take any credit, seeing himself as a mere researcher. Meanwhile, Russia suppresses his writings, Iran has accused him of being a subversive agent and Venezuela treats him like an enemy combatant. All because he wants to help people have the choice to decide their own political destinies.

While trying to set up an interview with Palin, Broomfield travels to her hometown of Wasilla, Alaska. After a friendly encounter with her parents (Chuck and Sally Heath), he talks to former friends (including Kilkenny, Stein and Cottle) who are now on Palin's enemy list. Suddenly Broomfield is shut out completely. He meets Palin at a book signings and public appearances, but the only people who agree to be interviewed are those who she has "thrown under the bus". And there seem to be rather a lot of these.

Broomfield and Churchill (who operates the camera while Broomfield carries the boom-mic) tenaciously try to get a balanced look at Palin, but they're knocked back at every turn. As a result, we clearly see how Palin's private anger and personal vendettas sit at odds with her smiley hockey-mom image. The filmmakers collect a terrific range of old photos and video footage that documents Palin from her school years to her in time as Wasilla mayor, Alaska governor, Republican candidate and right-wing pundit.

The approach is refreshingly light-handed: this is certainly not a hatchet job. But nothing is revelatory either. At least the film breaks the surface of news stories, most notably in interviews with Wooten and others at the centre of "Troopergate". Meanwhile, some interviews inadvertently confirm some more outrageous claims about Palin. Thankfully, the filmmakers just let these comments linger in the air without over-egging them.

What emerges is a portrait of a typical politician, someone gifted at making everyone she meets feel like they're the most important person to her while her private life is awash with private feuds, personal agendas and a belief that she is God's chosen one. Where the film becomes frightening is in clips, interviews and evidence that show how Palin simply can't accept her failings, blaming others for her mistakes. And with their fair approach, Broomfield and Churchill's film might ensure that she's never has political power again.

Essentially, we are just watching Panahi while he's under house arrest awaiting the appeal ruling. His friend Mirtahmasb is operating the camera, although sometimes Panahi provides reverse angles with his iPhone. Panahi also figures that he's only banned from writing or directing a movie, so he decides to read and re-enact one of his banned scripts for us. Pointedly, it's about a young woman locked in her home by her parents to keep her from running off to university.

Yes, the layers of meaning are witty and provocative. Panahi stares across the city from his ninth-floor balcony, watching fireworks and trying to resist the urge to capture it on camera. As a true artist, storytelling is in his blood. He also goes through a some of his own films, looking for key moments when non-professional actors surprised him by finding a truth he hadn't expected. Of course, this is echoed in Panahi's appearance here, as well as a hilarious sequence involving a young arts student who turns up collecting the rubbish. Not to mention the neighbour who tries to get Panahi to babysit her yappy little dog. But then, he's already watching his son's pet iguana Igi, who nearly steals the show.

Along the way, Panahi also chats with Mirtahmasb about the dire state of filmmaking in Iran, with filmmakers under threat from the government for saying things that are prohibited. This is a political sentence, Mirtahmasb observes, neither legal nor judicial. As they talk, it's obvious that none of them has a clue what the government is looking for, or what it is offended by. It's also profoundly sad, as Panahi and Mirtahmasb mourn the silencing of important artists. Including themselves.

The film is so playful that it keeps us laughing all the way through, even as it pointedly reminds us that Iran is a progressive, modern country with a terrifyingly repressive government. And watching one day in Panahi's life tells us more than a more didactic documentary ever could. Really, this should be essential viewing for anyone interested in either cinema or global politics.