In a somber and gloomy setting of 17th century England, the narrative begins with young Gwynplaine, whose face has been brutally disfigured into a perpetual grin by order of a vindictive nobleman. Abandoned and left to wander the harsh wilderness, he rescues an infant girl, Dea, who is both frail and blind. A compassionate traveling philosopher named Ursus takes them in, raising them as his own. Gwynplaine’s grotesque appearance becomes a sideshow attraction, while his tender heart remains concealed beneath the laughter forced upon him by society’s cruelty. Through their shared companionship, Gwynplaine and Dea come to share a deep connection, their bond unbroken by their mutual afflictions.

As time marches on and Gwynplaine's fame as a sideshow performer grows, his life takes a dramatic turn when his true lineage is revealed. He discovers he is the rightful heir to a noble title, entangling him in the political machinations of the court. Amidst these revelations, the brutal aristocracy and their schemes challenge Gwynplaine’s integrity and the simple happiness he has found with Dea and Ursus. His internal struggle between embracing his newfound status and remaining true to his roots propels the story into a tense crescendo, compelling him to confront the injustices he has endured.