Young Marianne is in bed after falling from her horse. She occupies herself by doodling in a sketch book, drawing a boy inside a bare house. When Marianne sleeps she finds herself outside the very house that she drew.
Marianne tries to erase Mark from her drawing altogether and replace him with her friend Fiona and a couple of ponies but this fails. The boulders also refuse to disappear.
Marianne loses her sketch book and becomes upset. In the real world her mother, teacher and doctor begin to worry. Finding her book again Marianne draws Mark some food, books and a bed.
The children become increasingly alarmed as to the intentions of the hostile boulders surrounding the house. Marianne draws a bicycle for Mark to strengthen his legs.
