A classic on rails: 100 years ago, on August 8, 1924, the first electrified S-Bahn train traveled through Berlin. Since then, the red and yellow cars have become an integral part of the city. The film recounts the highs and lows of the S-Bahn's eventful history, takes a look behind the scenes of operations between the workshop and the control center, and tells the stories of the people who keep the trains running.