On an icy winter's day in January 1649, a unique event in English history took place on a scaffold outside of Whitehall: Charles I, King of England, was executed. The king had been held to account and the Divine Right of Kings disregarded. Regicide, a once-unfathomable act, formed the basis of the Commonwealth's new dawn. The killers of the king were soldiers, lawyers, Puritans, Republicans and some simply opportunists, all brought together under one infamous banner. While the events surrounding Charles I and Cromwell are well-trodden, the lives of the other fifty-eight men - their backgrounds, ideals and motives - has been sorely neglected. Their stories are a powerful tale of revenge and a clash of beliefs; their fates determined by that one decision. When Charles II was restored he enacted a deadly wave of retribution against the men who had secured his father's fate. Some of the regicides pleaded for mercy, many went into hiding or fled abroad; others stoically awaited their sentence. This is their shocking story: the ideals that united them, and the decision that unmade them.