More men under the age of 50 in the UK are likely to commit suicide than be killed by cancer or in a car accident.
That statistic has shocked Dr Xand van Tulleken, who, at 39, is in this high-risk category.
In this Horizon special, he wants to find out why people have suicidal thoughts and if there is anything we can do about it.
He meets people who have had experience of suicide, either through failed attempts or by losing loved ones.
Along the way, he taps into his medical know-how to talk to scientists and researchers in the US who are at the cutting edge of suicide prevention.
He also joins the RNLI as they respond to calls alerting them to suicide attempts.