In Measure for Measure, Vincentio is the Duke of Vienna who disguises himself as a friar. He temporarily places Angelo in charge of Vienna, claiming that he must leave on a diplomatic mission, but secretly remains nearby to observe how Angelo governs.
Using the name Friar Lodowick, Vincentio investigates the strict enforcement of Vienna’s neglected laws. Angelo sentences Claudio to death for having sex outside marriage, then attempts to exploit Claudio’s sister Isabella in exchange for her brother’s life. The disguised Duke helps Isabella and Mariana devise the “bed trick,” which exposes Angelo’s hypocrisy and revives Mariana’s claim on him.
Vincentio’s disguise lets him hear private conversations and influence events without immediately revealing his authority. In the final act he returns publicly, unmasks himself, and confronts Angelo and Lucio. His actions combine surveillance, legal power and elaborate deception.
Escalus is an experienced lord, Claudio is the condemned young man, and Angelo is the Duke’s deputy. None of them is the disguised ruler.