City Lights opens with a monument, signifying "Peace and Prosperity," being donated to the city. We see a wealthy man and a woman speaking to the crowd, but their voices sound more like kazoos than words (This was Chaplin’s way of making fun of the release of The Jazz Singer in 1927, the first picture to feature synchronized sound, the first "talkie"). Shortly after the speeches, the monument is revealed and we see The Tramp asleep in the lap of one of the statues. When he realizes where he is, the Tramp attempts to make his way down, but gets stuck on a sword from the monument. In a series of comical moves, the Tramp eventually manages to get down, jumping over a fence as a number of city authorities yell at him all the while.
Afternoon. The Tramp wields a cane and wanders down the street. Two young boys steal his cane and he grabs it back from them before continuing on. Suddenly, he glimpses two sculptures in a store window, one of a nude woman, and another smaller one of a man on horseback. As he stares at the two sculptures, the sidewalk opens as a manhole behind him without him noticing. He keeps walking forward and backwards, examining the sculptures and completely unaware of the dangerous hole behind him.
Next we see a young girl sitting on a street corner selling roses. The Tramp climbs through the car of a much wealthier man and wanders onto the street in front of the girl. She asks him if he'd like to buy a rose and he accidentally knocks one out of her hand. When he picks it up, she searches the ground for it, at which point the Tramp realizes she is blind. He hands her the rose, which she pins to his collar. After the Tramp puts a coin in the girl's hand, a very wealthy man walks past and gets into a car nearby, and the girl mistakes the rich man's slamming car door for the Tramp leaving. Realizing that the girl thinks he is a much wealthier man, the Tramp decides not to correct her and slinks away unnoticed.
After a moment, the Tramp comes back and watches the girl fill a small bucket with water. Not seeing him, she throws the bucket of water in his face, thinking that she's throwing it on a patch of plants. Soaking wet, the Tramp wanders away.
Evening. We see the blind girl arriving home at the end of her day. Her grandmother tends a fire and helps her put her things down. The girl puts on a record and waters some flowers in her window. Outside, two lovers go out for an evening together, the girl looks sorrowful and pulls a cage filled with birds into her apartment.
Night. We see a drunk man tying a rope around his neck. The rope is connected to a large rock that he plans to throw into a river to drown himself. As the Tramp comes down some steps nearby, he spots the man and tries to stop him. When he confronts the man, the man drops the rock on the Tramp's foot. Attempting to comfort the suicidal man, the Tramp tells him, "Tomorrow the birds will sing," and the man begins to cry. "Be brave! Face life!" the Tramp says, but the man is intent on killing himself. Rashly, he goes to tie the rope around himself, but accidentally ties it around the Tramp's stomach and ends up pushing the Tramp into the river. Realizing his mistake, the drunk man takes off his jacket and runs over to help the Tramp out. When he grabs the Tramp's hand, however, the Tramp ends up pulling him into the water.
When they eventually manage to get out of the river, the Tramp quickly falls back in. The man again goes to help him out, but ends up falling in himself. Finally, they both get onto land and the man tells the Tramp, "I'm cured. You're my friend for life." The men shake hands and as the drunken man goes to grab the Tramp's hat, he nearly falls in the water, but the Tramp catches him. The man invites the Tramp home to his house to get "warmed up," and as they leave, they run into a cop. Before they leave, the Tramp grabs the flower that the girl sold him earlier.
The suicidal man turns out to be a millionaire, and brings the Tramp back to his large mansion. At home, the Millionaire asks his butler if there is "any news," and the butler informs him that his wife sent for her baggage. Throwing a picture of his wife across the room, the Millionaire pours them both some liquor and toasts to their friendship, while accidentally pouring liquor into the Tramp's pants.
City Lights is a silent film, but it was released after the first "talkie" was released. The introduction of films with sound caused quite a stir in Hollywood, where silent pictures had been the norm, and Charlie Chaplin pokes fun at the introduction of the new type of cinema within the first few minutes. Even though City Lights is a silent film, the first characters who have dialogue in the film speak, but their speech is not discernible English; rather, the mayor and his wife speak and the sound of a kazoo begins. This parodic choice is a signal that Chaplin understands that technologies are changing, but he is not necessarily going to change with the time.
It is not long before Chaplin himself, playing one of his most memorable characters, the Tramp, appears in the film, and he uses many tricks of physical comedy to establish his character as the comedic center of the film. Particularly in the Tramp's dismount from the large statue, Chaplin employs his virtuosic physical work to create comedic scenarios as he climbs down in front of the entire city. His pants get ripped by the sword of one of the statues, and he slides down it unceremoniously, a hapless look of surprise and distress on his big-eyed face. The movie wastes no time in establishing Chaplin's star-making comedic chops; it has no need to, since Chaplin himself directed, wrote, and produced it.
Chaplin's physical antics are a huge organizing principle of the plot of the film. While there is a narrative arc, a recurring structural feature of the film is that scenes are organized around the Tramp getting into yet another physical difficulty. Whether it is climbing down from a statue, getting his cane stolen, nearly falling into a manhole, or any number of absurd scenarios, Chaplin cannot seem to keep himself out of trouble, and this organizes his life and the plot of the film. At times it feels that, more than a plot, the viewer is meant to follow this comic journey closely, to relish in the flexibility and elasticity of Chaplin's physicality.
Nothing in the film is off-limits for joke fodder. The flower girl's blindness is treated with sensitivity, but it also becomes the premise of a comic moment in which she mistakenly throws water in the Tramp's face. Then later, the drunken man plans to commit suicide by drowning himself, but this soon becomes a comic dunk tank routine, in which he and the Tramp keep falling into the river without meaning to. When they finally manage to get back on dry land, the man—who was suicidal minutes ago—tells the Tramp that he is cured. In this way, the Tramp's slapstick antics and the absurdity of the scenario have lifted the man from his depression.
As clumsy and absentminded as the Tramp is, he is also established as a good-hearted and moral man. When the millionaire goes to commit suicide by drowning himself, the Tramp stops him. He might be a bit out-of-touch, a clueless clown, but he wants to help his fellow man, and he is shown to be a caring and compassionate person. Thus, we know that the Tramp is the film's protagonist; however clumsy and whacky he may be, is a good man who wants to help other people.