Simon Cox investigates the secretive world of one of Malawi's biggest charities - DAPP (Development Aid from People to People). For decades governments including the US, UK and other European nations have donated many millions of dollars to DAPP for projects ranging from sanitation to teaching. But DAPP has a big secret - it is under the control of a Danish cult-like organisation called the Teachers Group. It was set up in the 1970s and ran alternative schools in Denmark before expanding to Africa. Its members have to contribute up to a third of their salaries to 'a common economy', have to be available 24/7 under a principle called 'common time' and many complain of being 'brainwashed' by the organisation. Senior leaders of the Teachers Group are wanted by Interpol on fraud charges and are thought to be holed up in a $25m complex in Mexico. Danish investigators concluded the group has been engaged in a complex financial fraud with over 100 charities, companies and offshore shells in 50 countries used in funding the lifestyle of the leaders. Simon travels to Malawi to reveal DAPP's secrets, hearing from insiders about how it works and the toll it has taken on them and their families. He has also obtained access to a cache of documents revealing the links between the Teachers Group and DAPP and presents some of this evidence to UNICEF and DFiD.

This BBC investigation is in partnership with Reveal from the Center for Investigative Reporting (CIR).

Anna Meisel producing.