In the age of "binge-watching" programmes online or on DVD box sets, a new podcast series is gripping audiences around the world who are left to hang on for each weekly instalment.

Serial, from WBEZ Chicago, the makers of This American Life, is the real life story of the murder of a teenage girl in Maryland in 1999.

Her boyfriend was convicted of the crime but the evidence was largely based on one witness. Throughout the series, reporter Sarah Koenig investigates the facts around the case.

Producer Dana Chivvis spoke to BBC Newsnight about why the show has become such a cult hit.