- Meanwhile, back at Gloucester's castle, Edmund's evil plan is progressing nicely. Cue the evil smirk and hand-rubbing gesture.
- He has told Cornwall about his father's forbidden allegiance to Lear and has also showed Cornwall the incriminating, anti-Cornwall letter. (Remember the letter Gloucester showed Edmund back in Act 3, Scene 3?)
- Edmund humbly suggests that he's made a great sacrifice by placing his loyalty to Cornwall above his filial duty (to his father, Gloucester).
- Cornwall concludes that it now seems like Edgar's "plot" to kill his father was kind of just, what with Gloucester being such wicked guy and all.
- Edmund holds up the incriminating letter and says something like: "It's just so awful that I have to tell on my own father, who is clearly a spy and informant for France."
- Cornwall says that whether the letter is true or false doesn't matter. Edmund has shown great loyalty, so he's going to be the new Earl of Gloucester either way.
- Cornwall sends Edmund off to find Gloucester and bring him back for punishment.
- Edmund hopes that when he finds his father, the man will be comforting Lear, because then Gloucester will be doubly implicated for crimes.