Briony is out by the island temple slashing nettles. She's done being a playwright, and decides she will become the greatest slasher of nettles in the world.
Needless to say, the story becomes pretty involved in Briony's imaginative head.
Leon drives by, but she doesn't go to greet him. She's too busy being an internationally recognized nettle slasher.
She stops daydreaming and feels disappointed in her own insignificance, so she decides to sit by the bridge until something significant happens to her.