
The Messenger is "his lordship's man", a servant of Angelo, who arrives at the prison just before dawn in Act IV, Scene II. The disguised Duke greets him as the bearer of Claudio's pardon; instead he hands the Provost a note, with Angelo's further charge that he "swerve not from the smallest article of it, neither in time, matter, or other circumstance," and leaves at once.
Angelo's man, who brings the Provost the order to execute Claudio at dawn just when the disguised Duke expects a pardon.
The note orders Claudio executed by four o'clock and his head sent to Angelo by five, with Barnardine to follow in the afternoon. It shows that Angelo means to break his bargain with Isabella, and it forces the Duke to improvise the plan that saves Claudio by sending Angelo another man's head in his place.
The Messenger carries out Angelo's order exactly, pressing the Provost to follow it to the letter and leaving as soon as it is delivered.
The Messenger speaks a single, formal speech; its force lies in the gap between what the Duke expects him to bring and what he actually delivers.