For as long as Silk Touch can remember his mother has treated him like a filly his whole life, the reason.
His older sister is in the hospital with a costly disease.

One day his mother is approached by a stallion who offers to pay for the medical expense, the catch.
Silk has to last a year at the exclusive "Celestia's school for Mares".

The school has a boarding area for the students to live in and no colts or stallions are allowed in, not even teachers.

In order to save his sister, Silk undergoes his challenge.