On Midsummer Night, Barney lies awake in his hot bedroom, frustrated at being sent to bed during daylight hours. His grandmother has explained that darkness will not fall until after ten o’clock, too late for an eight-year-old’s bedtime. Determined to stay awake all night, Barney thinks about Stig and wonders how old he might be before accidentally drifting off. Later, Barney wakes and sees bright moonlight. He decides to sneak out to visit Stig. As he creeps downstairs, Dinah the spaniel, who sleeps downstairs, barks but quiets when hushed. Lou spots Barney from her window and persuades him to let her join the adventure. She brings Dinah as a bodyguard.

Barney and Lou venture through the moonlit garden and paddock, where Flash the pony snorts at them before returning to grazing. Reaching the copse’s edge at midnight, marked by distant church chimes, they find the familiar woods transformed into a deep, shadowy forest. Both Dinah and Flash react nervously, sensing something in the darkness just before a great stag appears in a moonlit glade. Dinah chases it, and the children impulsively leap onto Flash’s back to follow.

The pony plunges across a shallow depression where the deep chalk pit can usually be found.