Jim Carter, a stoker on a luxury liner, loses his job after he reveals that he has faked a broken arm, and he vows to those wealthy people looking down on him in the stoke hole and laughing that someday he will be where they are.  After Jim fails to last as a target in blackface at a sideshow for baseball pitches in a carnival, Pop McWade, owner of the carnival show "Dante's Inferno," offers him a job cleaning up the place.

The show includes statues of Cleopatra, Dante, Salome, Virgil, Marc Antony and Alexander the Great, after whom Jim fancies himself.  Pop has idealistically devised the show to present to customers a "glimpse of hell" with metaphoric suggestions on how to get out, but it does not attract many customers until Jim tries the role of barker and by playing up the sensational aspects produces a sellout, to the delight of Pop and his niece Betty, who sells tickets.

Jim soon marries Betty and plans to build a new show, which he describes as the biggest "hell on earth." After a son Alex, called Sonny, is born, Jim convinces the other concessionaires to invest in a larger "Inferno," but when Dean, the "chute-the-chutes" owner, refuses to give up his prime location for the new concern, Jim purchases Dean's lease and proceeds to ruthlessly wreck Dean's concession, despite Dean's pleas for him to wait one month so that he could raise enough money to move.

At the opening of the new spectacular inferno, Pop, dressed as Virgil, guides patrons through Dante's nine cycles, but he is interrupted when Dean, whose wife died that day, jumps to his death.  Soon, Jim expands his empire and plans an extravagant casino on the high seas to cater to the pleasures of the rich.  Upset because Jim's casino will promote gambling and vice, Pop tells Jim that they are drifting apart.  After Harris, a building inspector, tells Jim that the Inferno is unsafe and needs to be rebuilt, Jim threatens to see that Harris loses his job if he insists on his opinion.  Betty then sees Harris accept an envelope of money.

At the Inferno, a cave-in occurs, and Jim rescues Pop.  Jim remains watching over Pop through two sleepless nights as Pop recovers.  After Harris commits suicide and leaves a written confession detailing Jim's bribe, Jim is prosecuted.  His denial that Harris came to his home is backed by Betty, who, after Jim is acquitted, explains that she lied to save Sonny and plans to leave for Reno for a divorce. As Jim's cruise ship, the S.S. Paradise, prepares to leave, he has trouble raising money and has to cut into his profits by using the ship as security.  When the crew strikes, Jim orders a new crew to be hired from the out-of-work men by the docks, whether they are dependable or not.

After the ship leaves, Betty discovers that Sonny is lost and sends a wire to Jim saying that kidnapping is feared.  He receives the radiogram in the midst of bacchanalian drinking, dancing and gambling and rushes to his cabin, where he finds Sonny, who had been brought by Jim's assistant Jonesy as a surprise.  Jim angrily rebukes Jonesy, saying that the ship is the last place in the world for the child to be.

After he sends a message to Betty, a fire breaks out when a drunk throws liquor at a flaming meal.  The incompetent men in the engine room do not respond when called, and the passengers panic, some falling into the sea, others shooting each other so that they can get into lifeboats.  After Jim rescues the captain, they attempt to keep the fire from sweeping aft while they steer the ship to the beach two miles away.  Jim fights rebellious crew members and handles the controls himself.  The circulatory pump stops and a water pipe bursts, but Jim succeeds in turning the ship and beaching it.

Meanwhile, Betty races in a car to the ship.  Sonny is safe and Jim, bandaged but okay, confesses, as he embraces Betty, that Pop was right: his "hell" was of his own making.  He apologizes and says that all he now has to offer is his love, and Betty replies that that is all she ever wanted.