We explore the vast rail network that crisscrosses Tokyo. With 148 train lines carrying some 40 million passengers daily, Tokyo hosts the world's largest and most interconnected urban rail network. Actor Sato Takeru takes on a riddle-solving mission tied directly to the train schedule, putting the railways' famed dedication to punctuality to the test in the process. We uncover a fascinating history and meet the people whose tireless dedication keeps the whole intricate operation running like clockwork.