Channel 4's multi-award-winning foreign affairs strand returns for a new series with a film following a volunteer ambulance service in Somalia's war-torn capital, Mogadishu. Reporter Seyi Rhodes and director Sasha Achilli accompany the extraordinary team who risk their lives braving bombs, gunfights and al-Shabaab militants to get sick people to hospital in a city where the government struggles to cope and where they are many people's only hope.

Reporter Marcel Theroux and director Kate Hardie-Buckley travel to Mongolia's capital Ulaanbaatar, where the air quality can reach more than 100 times the accepted limit and is causing a public health disaster. A layer of smog caused by coal smoke blankets the city. The smog is full of floating soot particles, some of which are small enough to bypass the body's defences, causing fatal illnesses including respiratory disease, heart disease and cancer. According to Unicef, cases of respiratory infections have tripled here over the last 10 years as pollution surges. The team visit a children's hospital where senior paediatrician Dr Oyenbileg tells Theroux that respiratory illness is the biggest killer of children under five, as they are more susceptible to respiratory diseases such as bronchitis and pneumonia.

Reporter Rania Abouzeid and director Karim Shah travel to Kabul where the population, long used to living with bombs and gunfights, face a new danger: criminal gangs who kidnap for ransom. Often their victims are children. The Unreported World team join the lead detective of the police anti-kidnap squad as they attempt to reunite kidnap victims with their families.

Krishnan Guru-Murthy visits Caribbean tourist destination the Dominican Republic, to investigate terrible crimes being committed against teenagers by sex tourists.

Unreported World investigates how the #MeToo campaign has taken off in India's film industry, meeting top actresses who are speaking out against assault, sexual harassment and rape.

As the Brazilian army assists the police in tackling drugs gangs in Rio de Janiero, Ade Adepitan joins young journalists reporting from inside one of the cities most violent favelas.