The comfortable and amiable Daniel Boone Brown, a resident of New York's water front, becomes the victim of a mad scientist's psychological experiments. For days, Dr. Ulrich Metz messes up Daniel's life, bringing on failing health, restless sleep, a nervous and irritable disposition, tardiness for work, and superstitions that cause worry and fear. Several months into the ordeal, one of Metz's minions, hired as Daniel's livery, feeds him a midnight snack of spring onions, lobster, Welsh rarebit and mince pie. We see the contents of his stomach causing pain and distress; then he has vivid and surreal nightmares. Will Metz succeed in driving Daniel to suicide?

Buster's handmade boat, The Damfino, is finished and is, of course, too large to get through the basement door. When he drives off with it in tow, the side of his house, then the whole thing, collapses. At the harbor he rides the boat out only to have it sink beneath him. The rest is a series of adventures he and his family have with the restored boat.

Roscoe flirts with a girl in the park. Later he takes his wife and mother-in-law to the movies only to see his flirtation showing on the screen.

Charlie is in boot camp in the "awkward squad." Once in France he gets no letters from home. He finally gets a package containing limburger cheese which requires a gas mask and which he throws over into the German trench. He goes "over the top" and captures thirteen Germans ("I surrounded them"), then volunteers to wander through the German lines disguised as a tree trunk. With the help of a French girl he captures the Kaiser and the Crown Prince and is given a statue and victory parade in New York and then ... fellow soldiers wake him from his dream.

A single father struggling to make his comeback as a screenwriter falls in love with one of his students. Meanwhile his son, studying to become a chef, falls in love with his teacher. Love is great for creativity, but it comes with a price.

On a sailing trip, sweethearts Bobby and Gloria arrive in a very sinister-looking India, where an evil rajah attempts to force Gloria into his harem.

In a drugdstore Al and Roscoe are rivals for Alice. Roscoe slings melons and operates the gas pump. Buster delivers a wedding gown for Alice, begins modeling it, is mistaken for Alice and is kidnapped by Al.

When Mabel catches her husband flirting with their maid, it leads to a sharp dispute. As part of making up, the couple decide to take a walk to the park. Nearby, another married couple have just had a similar domestic squabble, and they too go to the park together. But at the park, both men find it difficult to avoid getting themselves into further trouble.

The opening scene, a dream sequence prior to the vaudeville routines which follow, is what makes this film famous. In it Keaton plays everyone in a theatre simultaneously (through multiple exposures). He is the band leader, all its members, the dancers on the stage and everyone in the audience.

The new school teacher fresh from the city struggles with her unruly bumpkin students, while she awaits the arrival of her fiancé.

A housewife tires of her husband's annoying behavior and returns to her mother. At first, the husband is quite pleased to have the house all to himself. But he quickly discovers that even the most basic domestic chores can be fraught with difficulty.

Leila porter comes to dislike her husband James, a glue king who is always eating onions and looking sloppy. But after she divorces him and marries two-timing playboy Schuyler Van Sutphen the now-reformed James looks pretty good.

Virtuous Mabel rejects the improper advances of a villainous cad. The furious villain and his henchmen then seize Mabel and chain her to a railroad track. Mabel's anxious boyfriend turns for help to the great Barney Oldfield, who jumps in his racing car and speeds to the rescue.

Dr. Holepoke, his wife, and his son are at the horse races when the doctor begins to flirt with another woman. Then the doctor and the other woman's boyfriend lose their money betting on the same horse, leaving both of the women very unhappy. While Dr. Holepoke thinks about how to get some new patients, the other man has a plan to recover some of his losses at the doctor's expense.

The beach front house, where Fatty and Mabel live, has been "launched" out to sea by the villains. When Fatty and Mabel arise, they find the beds floating in a sea of water.

Arthur and Martha are out walking when they see an aviator and his biplane. When the aviator offers to take them up, Martha excitedly accepts, but Arthur refuses to go along. Martha thoroughly enjoys her ride, but it makes Arthur angry and jealous. But Arthur soon has bigger problems to worry about.

At the Elk's Head Hotel bellhops torment the lobby, each other and guests. The elevator is powered by a stubborn horse. A sham robbery turns into a real one. And there is a chase on a runaway trolley.

An out-of-work swindler takes a job as a reporter. After witnessing a car go over cliff, he grabs a rival reporter's camera and races to the newspaper office to enter the photo as his own. His rival is delayed when he gets caught in a woman's bedroom by her jealous husband. The swindler follows the distribution of the paper containing his 'scoop' around town where he is once again chased by the rival reporter. Both end up on the cow-catcher of a streetcar.

Three young children set up a table, and on the table is placed a miniature stage. The stage curtain opens, a carpet appears, and then the carpet unrolls by itself. Two puppet figures then come out and begin to perform a series of routines.