After the last elections in Russia, mass protests against vote-rigging led to clashes in the centre of Moscow. The events on Bolotnaya Square were the biggest challenge President Putin has ever faced to his rule. Four years on, several demonstrators are still serving long prison sentences, the laws on protesting have been tightened and the arrests continue. As Russia gears up for parliamentary elections in September, Sarah Rainsford talks to some of those caught up in the Bolotnaya protests, and asks what their stories tell us about Putin's Russia today.

In the Colombian capital of Bogota, Lucy Ash meets two people who fear they will never be able to return to their homes. They both come from Choco, which is one of the poorest provinces and most violent parts of the country. Maria, an Afro-Colombian mother of four, fled her town after she was abducted and brutally attacked by paramilitaries. Plinio was trying to help members of his indigenous community go back to their farms when he received death threats from a splinter group of left wing guerrilla (the ELN) and his friend was assassinated.

Their stories illustrate a nationwide trauma - the government may be on the brink of a historic peace deal with the FARC rebels, but Colombia has even more internally displaced people than Syria. More than 200,000 have been killed and seven million driven off their land during half a century of war. Lucy travels down the River Baudo to meet people uprooted from their jungle villages in violent clashes earlier this year and finds that Latin America's longest insurgency is far from over.

Reported and produced by Lucy Ash.

Playing war-games in the woods has become an ever-more popular pastime in Poland as thousands of young people join paramilitary groups to defend their country against possible invasion. Others - so-called "preppers" - are building bunkers and storing food supplies so their families can survive any disaster. Now the government plans to recruit such enthusiasts into a state-run volunteer defence force - to counter a possible Russian threat. But are the authorities stoking fear - and creating an amateur force that's no use in 21st Century warfare? Tim Whewell reports from the forests of north-eastern Poland, close to the Russian border.

Producer: Estelle Doyle.

Oil-rich Venezuela is struggling to feed its own people as a result of a spiralling economic and political crisis which has brought the country to its knees. Vladimir Hernandez returns to his home country where thousands queue for many hours in order to buy even the most basic of food stuffs. Malnutrition and starvation, unthinkable only a few years ago, are becoming a reality for some communities and particularly the poor.

Away from the sound of bombs and bullets, in the basement of a crumbling house in the besieged Syrian town of Darayya, is a secret library. It's home to thousands of books rescued from bombed-out buildings by local volunteers, who daily brave snipers and shells to fill its shelves. In a town gripped by hunger and death after three years without food aid, Mike Thomson reveals how this literary sanctuary is proving a lifeline to a community shattered by war.

Produced by Michael Gallagher and additional research and translation by Mariam El Khalaf.

*Omar, the FSA soldier pictured above who was the last voice heard in this programme has been killed in fighting.*.

Ed Butler explores the secretive and shocking world of Malawi's "hyenas". These are the men hired to sexually initiate or cleanse adolescent and pre-adolescent girls - some said to be 12 years old, or even younger. It's a traditional custom that is endorsed and funded by the communities themselves, even the children's families. We meet some of the victims, the regional chief campaigning to stop the practice, and the hyenas themselves, and ask if enough is being done to stamp out a custom that's not just damaging on a human scale, but is also undermining the country's economic development.

Reported and produced by Ed Butler.

Chloe Hadjimatheou tells the astonishing story of a group of young men from Raqqa in Syria who chose to resist the so-called Islamic State, which occupied their city in 2014 and made it the capital of their "Caliphate". These extraordinary activists have risked everything to oppose IS; several have been killed, or had family members murdered. IS has put a bounty on the resistance leaders' heads. But the group continues its work, under the banner 'Raqqa Is Being Slaughtered Silently'. Chloe meets the group's founders, some of whom are now organising activists in Raqqa from the relative safety of other countries.

Dave Edmonds travels to the mid-western city of St Louis (location for the musical 'Meet Me In St Louis', starring Judy Garland) for the US chess championships. The city has become a world centre for the game of chess. Its status has partly been achieved by funding from a controversial multi-millionaire, whose childhood included time in an orphanage. Rex Sinquefield is well known for his fascination with the game and his enthusiasm is shared by many others. There is a thriving chess centre, elite tournaments which attract some of the top players, a Chess Hall of Fame and chess lessons in local schools.

St Louis is one of America's most violent cities and has most recently been in the news for race riots which erupted when an unarmed black man was shot by police. Can the game of chess serve to lessen racial tension and unite its citizens across the board?

Producer: Mark Savage.

Now that China has ended its One Child policy, one group of state employees may soon be out of a job - the country's hated population police. Hundreds of thousands of officers used to hunt down families suspected of violating the country's draconian rules on child bearing, handing out crippling fines, confiscating property and sometimes forcing women to have abortions. But with an eye on improving child welfare in the countryside, there is a plan to redeploy many of these officers as child development specialists. Lucy Ash visits a pilot project in Shaanxi Province training former enforcers to offer advice and support to rural grandparents who are left rearing children while the parents migrate to jobs in the big cities. If successful, the scheme could be rolled out nationwide to redeploy an army of family planning workers and transform the life prospects of millions of rural children.

Nkem Ifejika cant speak the language of his forefathers. Nkem is British of Nigerian descent and comes from one of Nigeria's biggest ethnic groups the Igbo. He's one of the millions of Nigerians, who live in the diaspora - almost two hundred thousand of them living here in Britain. Nkem wants to know why he was never taught Igbo as a child and why the United Nations Educational Scientific and Cultural Organisation, UNESCO, has warned that Igbo faces extinction in the next fifty years.

In this week's Crossing Continents, Nkem travels to the Igbo heartland in the southeast of Nigeria to explore the demise of a once proud language. He discovers that recent history has had profound effects on Igbo culture and identity. He discovers too that some Igbos are seeking to reassert their language and culture. Part of this is a resurgence of Igbo identity under a new 'Biafran' movement. Is this likely to find traction or will it ignite painful divisions from the past and lead to renewed tensions across Nigeria. From Nkem's own London-based family - where his wife is teaching both him and their son to speak Igbo - to the ancestral villages of Anambra State, 'Forgetting Igbo' reveals shifting perspectives on Nigeria's colonial past, emerging new ambitions for its future - and deep fault lines at the heart of its society.

Produced by Michael Gallagher.