It is about a girl called Velvet and she has a little brother called Donald and 3 sisters called Edwina, Merideth and Malvolia.
When a guy that Velvet knows dies in front of her own eyes, the man gives her his six horses, which Velvet and her sisters love to ride. So they enter the Gymkhana and when Velvet wins a race against the adults there she is delighted. When she gets home she and her sisters enter the village raffle, the first prize of the raffle is a beautiful piebald horse.
Velvet wins the horse and speaks to a very close family friend about helping her enter the grand national on the piebald, he helps her and to their surprise she wins but back in those days girls weren't allowed to be jockeys. Velvet and Mi get caught out and nearly get charged for fraud, but she gets let off.
Velvet is a very lucky girl that loves horses and now thanks to her best friend Mi is now famous too. But she didn't enter the Grand National so she can become famous. She does it for her horse, "The Pie" as he's known, so he is put down in history.
That is how she became National Velvet!!