Mark Twain is a 26-year-old traveler journeying from Missouri to the Nevada Territory. He initially expects a quick pleasure trip filled with romantic western scenery, but he quickly learns the harsh realities of stagecoach travel and frontier life. Over several years, he tries various schemes to strike it rich, including timber operations, silver mining, and pocket mining for gold. He also works as a reporter for a Virginia City newspaper and as a travel correspondent.

The Secretary is Mark Twain's older brother, who accepts a government appointment in Carson City. Upon arriving in the Nevada Territory, he discovers that the job comes with no prepared office space, requiring him to use his own boarding house room for administrative tasks. He operates with very little support from the government, paying for many official expenses out of his own pocket.

George Bemis is a passenger who shares the overland stagecoach with Mark Twain and The Secretary. He helps pass the long, monotonous hours on the plains by sharing tall tales with his companions. Most notably, he claims to have been chased up a tree by an enraged bull buffalo, which he then managed to hang with a noose.

Jack Slade is a division agent for the Overland Stage Line who maintains strict order among the station workers. He holds a fearsome reputation as a ruthless desperado and is known for violent outbursts. Despite his intimidating history, he behaves courteously when Twain meets him, though his demeanor changes completely when he drinks.

Brigham Young is the religious and civic leader of Salt Lake City during Twain's visit. He exercises absolute control over the Utah Territory, functioning effectively as a monarch. When gentiles have business disputes with Mormon residents, an appeal to Young results in an instant resolution, bypassing official government channels entirely.

Johnny is a friend who accompanies Twain to Lake Tahoe with the intention of starting a lumber business. The two men intend to stake a timber claim and get rich, but they accidentally allow their campfire to spread. The resulting blaze destroys their timber claim before they can even begin their operation.

Higbie is a prospector who enters into a silver mining partnership with Mark Twain in Esmeralda. He discovers a blind lead in an existing mine and negotiates with the operating foreman to secure a third of the claim for each man. However, he fails to coordinate with Twain and the foreman, resulting in the ten-day deadline expiring before any of them perform the necessary labor.

Whitman is a secretive individual rumored to possess a map leading to a legendary cement mine. Local lore suggests the rock in this mine contains massive quantities of gold, making him a target for prospectors. When he quietly leaves town, Twain and a group of hopeful miners attempt to trail him, only to discover that a large parade of others had the same idea.

Boggs is a reporter for the Union newspaper in Virginia City. He works the same local beat as Twain, leading to a friendly but intense rivalry between the two journalists. They compete constantly to publish news first, sometimes resorting to sneaky tactics to intercept items like the monthly public-school report.

Jim Blaine is an eccentric resident of Virginia City. Locals encourage Twain to visit him when he is intoxicated, as this is the only condition under which he tells a famous story about his grandfather's ram. Once he begins speaking, he wanders through endless, unrelated tangents and completely fails to discuss the ram.

The Admiral is a retired whaling captain who travels on the same ship as Mark Twain to Hawaii. He holds strong, unyielding opinions on nearly every subject. When his knowledge falls short during arguments with other passengers, he confidently invents historical facts to support his claims.

Markiss is a resident of Lahaina, Maui, who has a reputation for compulsive lying. He repeatedly interrupts conversations between Twain and other locals for no reason other than to tell a story that overshadows whatever was just said. His habit is deeply ingrained, making him a difficult person to hold a genuine conversation with.

Gridley is an unsuccessful mayoral candidate who loses an election and honors a bet by carrying a 50-pound sack of flour home. He then turns the spectacle into a massive fundraising effort for the United States Sanitary Commission by repeatedly auctioning the flour sack to benefit wounded soldiers.

Tom Quartz is a cat belonging to a pocket miner in California. According to the stories told by his owner, the animal possesses an unusual affinity for the mining trade. The miner claims the cat acts as a skilled metallurgist who can sense the presence of gold in nearby streams.