Xand Van Tulleken investigates why suicide is the biggest killer of men under 50 in the UK, causing more deaths than car accidents, and even more than cancer. In this programme, he explores the reasons why people develop suicidal thoughts, and whether there is anything that can be done about it. Xand meets Steve Mallen, who lost his 18-year-old son Edward to suicide in 2015. In the years that followed his son's death, Steve launched the Zero Suicide Alliance, a collaboration of NHS Trusts, businesses and charities who are all committed to preventing suicide in the UK.