The climax of this play definitely comes in Act V scene 3, which is when Lear and Cordelia have been captured by Edmund and they are brought on stage. What makes this scene the climax is that the audience are on the edge of their seats about the fate of these characters and what will happen to them. Edmund has previously in Act V scene 1 made it clear that he will show no mercy to Lear and Cordelia if he captures them in battle, and in Act V scene 3, the audience nervously awaits to see what he will do. The power and strength of this climax is heightened by Lear's obvious retreat into insanity to help him cope with the situation. He imagines that he and Cordelia can live as two birds in the forest which allows him to ignore the plight of their situation:
We two alone will sing like birds i'th'cage.
When thou dost ask me blessing, I'll kneel down
And ask of thee forgiveness; so we'll live,
And pray, and sing, and tell old tales...
Lear imagines some kind of alternative reality where he can undo the mistakes of his past and live happily with Cordelia, showing that he recognises his wrongdoing towards her. However, there is no such opportunity for redemption, and the climax is made more pronounced by the note that Edmund gives to the captain which, as Edmund ominously states, contains his instructions concerning the captives. At this stage the audience still does not know what is going to happen to Lear and Cordelia, but everything points towards a tragic end, which makes this scene the climax of the play.