Children's animation series set in Chuggington, a special place where the trains are known as chuggers. They talk, think for themselves and don't need drivers! Ride along with young trainees Koko, Wilson and Brewster as they embark on new adventures, make new discoveries and learn the true meaning of friendship. Wilson and Brewster are sent to get stone from the mountain quarry. Brewster is in a hurry to get the job done, and doesn't hear Dunbar warning them to be extra careful on the way back, as going downhill with a heavier load is harder!