A celebration of public transit systems around the world. Five different characters' journeys through the imaginary city of Zoom explore the fascinating world of urban public transit systems. From a zany family of traveling street performers, to a spy on a top-secret mission, to a curious little boy touring the city for the first time, all of their trips start from different locations but end up in the same one. And as the quirky characters make their journeys, their stories are embellished with definitions, labels and explanations of how things work. All aboard! Whether by subway, bus, light rail or ferry boat—the city's accessible to everyone!