Clare Balding has emerged as Britain's new golden girl of broadcasting, so it's no surprise that she's off on another adventure this evening. Militant activist Emily Wilding Davison sustained fatal injuries when she stepped into the path of George V's horse during the 1913 Epsom Derby. Three newsreel cameras captured the shocking incident, but one question has never been answered: Why did she do it? Well, that's what Clare intends to find out this eve, joining forces with a team of forensic episodes to tell us what really happened on that fateful day...