The setting is the Earl of Gloucester's castle. As the scene opens, Curan, a courier, tells Edmund that Regan and Cornwall will be arriving that evening. Curan also mentions rumors of a feud between Cornwall and Albany.
Edmund expresses excitement over Cornwall's visit because he imagines that he can involve the duke in his plans to discredit Edgar. As a means to that end, Edmund implies brotherly concern as he coaxes Edgar to slip away under the cover of night. Edmund suggests that Cornwall suspects Edgar of aiding his enemy, Albany. Edgar, innocent and unaware of any of this plotting, agrees to flee to protect himself. In another ploy to blemish Edgar's reputation, Edmund engages his brother in a fake battle, intentionally wounding himself to draw Gloucester's sympathy.
In response to Edmund's explanation of his brother's attack, Gloucester promises to find Edgar and bring him to justice. Gloucester also pledges to make Edmund his heir.
Regan and Cornwall enter. Without hesitation, they fall for Edmund's story and join in condemning Edgar. Cornwall proclaims that Edmund shall join forces with him. Regan and Cornwall flatter Gloucester by asking his advice on an appropriate response to letters received from Lear and Goneril.
