The brief appearance of a messenger named ‘Somerville’ in The Third Part of Henry VI has been interpreted as evidence for a radically subversive Catholic Shakespeare. However, although John Somerville’s arrest for plotting to kill Queen Elizabeth, and the subsequent harassment of Warwickshire Catholic families, were part of Shakespeare’s formative experiences, this chapter uses new evidence to argue that religion formed only part of the story. It shows that Somverville’s arrest contributed to efforts by Robert Dudley earl of Leicester to destroy his rivals in Warwickshire politics through partisan manipulation of judicial processes and accusations of treason. Shakespeare’s allusion to Somerville can be read as a gesture not to Catholicism but to Warwickshire and national factional politics, rivalries over ancient possessions and family honour, and government abuse of legal procedures. Somerville’s arrest therefore resonated with depictions of murderous conflicts over inheritance, power and honour in the history plays.