HORATIO       He waxes desperate with imagination.

MARCELLUS  Let’s follow. ’Tis not fit thus to obey him.

HORATIO       Have after. To what issue will this come?

MARCELLUS  Something is rotten in the state of Denmark.

HORATIO       Heaven will direct it.

MARCELLUS                          Nay, let’s follow him. (Exeunt.)        (1.4.87-91)

Just rounding off the scene, a brief exchange between Horatio and Marcellus to give Hamlet and the Ghost time to get to another of the entrances for the beginning of the next scene which (spoiler) follows immediately. Horatio’s worried: he waxes desperate with imagination. Hamlet’s gone rogue, who knows what he’s capable of when he’s in this mood. He’s delusional! Marcellus is practical, thinking about action not analysis: let’s follow. We’ve got to go after him, ’tis not fit thus to obey him. When he’s acting like this, it’s our duty to defy his orders, and to follow. Have after, then, responds Horatio. Let’s go. To what issue will this come? But what’s going to happen? I’m out of my depth. Something is rotten in the state of Denmark, says Marcellus—and how cool is it that this laconic soldier, just doing his job, one of the play’s most minor characters, gets this pronouncement? He means in the Danish state, but to a modern ear in particular, it sounds like a physical state, a state of health even, especially in conjunction with rottenness, and even issue, the nastiness that might lurk in an abscess. It’s not good. Whatever’s going on, under the surface, it stinks. Heaven will direct it, suggests Horatio, piously; it’s in God’s hands. Nay, let’s follow him, we can’t afford to wait for divine intervention! We have to do this, says Marcellus. And off they go, stoically on Marcellus’s part, and full of trepidation, on Horatio’s.

And that’s the end of the scene.