新人女性騎手、芦原瑞穂（平手友梨奈）は中央の競馬学校に進み卒業、プロデビューするが成績は上がらず苦しんでいた。そんな瑞穂を迎え入れたのは、やる気のない調教師の緑川光司（中村蒼）と頑固で融通の利かないベテラン厩（きゅう）務員たちがいる廃業寸前の厩舎だった。瑞穂は地方競馬で騎手として再デビューするものの成績は上がらずいた。そんな中、緑川厩舎は馬主と瑞穂のいさかいが原因で馬を引き上げられ廃業の危機に至る
Rookie female jockey Mizuho Ashihara (Yurina Hirate) goes to a horse racing school in central Japan, graduates, and makes her professional debut, but she struggles with poor results. The place that welcomes Mizuho is a stable on the verge of going out of business with unmotivated trainer Koji Midorikawa (Aoi Nakamura) and her stubborn and inflexible veteran grooms. Mizuho re-debuted as a jockey at her local horse race, but her results did not improve. Meanwhile, the Midorikawa stable is in danger of going out of business because of a dispute between the horse owner and Mizuho.
