Esm e D lancourt was perfectly happy never to leave her quiet home in Saint-Denis-l s-Chevreuse, France. But when the doors of the commuter train bound for Paris slide closed, trapping her inside, she finds herself an unwilling participant in an adventure through the City of Lights. As Esm e struggles to find her way home again, the little butterfly meets a cast of characters and witnesses a world of wonders she could never have imagined...