Rhian Burke was happily married with three beautiful children, but in 2012 her life was ripped apart in a week of unimaginable heartbreak.

First, her one-year old son George died after a seizure, then just five days later her grief-stricken husband Paul took his own life.

Five years on, brave Rhian still suffers from extreme anxiety, but is joining forces with nine other unlikely runners to take part in the London Marathon.

In this two-part programme, Nick Knowles follows their preparations and hears how all have been affected by mental-health issues, but are determined to finish the race and raise awareness for their cause.