'Even if they're still alive, they've lost their kids'

Why do young people from Western Europe decide to leave home and join terrorist groups like so-called Islamic State? It's a question of our age and the subject of a new play at the National Theatre in London called Another World: Losing Our Children to Islamic State.

The play is based on the verbatim testimony of 40 people including families, children, lawyers and civil servants.

The play's author - the South African novelist - Gillian Slovo, went to talk to mothers in Mollenbeek, the Brussels suburb where many extremists have been found to live.

Director Nick Kent and Gillian Slovo talk to Martha Kearney about some of the testimonies.

(Photo: A person lights a candle during a candle light vigil to the victims of the Paris attacks in Brussels' Molenbeek district. Credit: Getty Images)