In Shakespeare's "Julius Caesar," the phrase "Now let it work. Mischief, thou art afoot" reflects a turning point in the narrative where the consequences of past actions begin to unfold. The speaker acknowledges that chaos and trouble are now initiated, and whatever happens next is out of their control. This moment captures the tension and uncertainty that accompanies pivotal decisions in the play.

The quote signifies both a resignation to fate and an acceptance of the unfolding events that stem from ambition and betrayal. It underscores the themes of power dynamics and moral dilemmas as characters grapple with their choices. The notion of 'mischief' highlights the unpredictable nature of political machinations and the disastrous outcomes that can ensue from personal vendettas and conspiracies.