After executing his last act of justice as a Montana marshal, Seth Bullock relocates to a gold-mining camp known as Deadwood in Dakota Territory, where he and partner Sol Star look to start a hardware business. Bullock soon crosses paths with another new arrival - legendary gunfighter Wild Bill Hickok - and clashes with the formidable boss of the Gem Saloon and occasional deal broker, Al Swearengen.

As suspicions arise that "road agents" may have been the true perpetrators of a massacre, Swearengen takes a special interest in the health of its sole survivor, a young girl ministered to by the unlikely team of Doc Cochran and Calamity Jane. Meanwhile, Bullock and Star attempt to buy property from Swearengen, who suspects an alliance between Wild Bill and the hardware fellows.

Competition arrives for Swearengen in the form of the Bella Union, a new gambling outfit from Chicago operated by savvy Cy Tolliver, Madame Joanie Stubbs and gaming guru Eddie Sawyer. Hickok puts up precious collateral in a poker game with McCall; Bullock and Sol strike a deal with Swearengen on a lot for their hardware store. Garret threatens Swearengen before investigating his gold claim.

Swearengen directs Farnum to buy back the Garret claim. Garret's wife, Alma, prevails on Calamity Jane and Wild Bill for help with the claim issue. Hickok's respect for Bullock grows and, as a result, he commissions Bullock to do a review of the Garret claim. An ailing colleague, Andy Cramed, rejoins the Bella Union, and Wild Bill's run of luck at poker ends abruptly.

Swearengen transforms the Gem into a courtroom as Deadwood is forced to make its own laws to try a cowardly murderer. With Calamity Jane off on a bender, Trixie is enlisted by Swearengen to help Alma with the orphaned child and to keep her pliable to his purposes. Fearing Andy's illness might threaten his business, Cy banishes him to the woods, where he is discovered by Jane.

Bullock encounters native resistance in his quest to bring a murderer to justice. Swearengen presses Farnum to keep tabs on Alma and Trixie. After an outbreak of smallpox hits Deadwood, the camp fathers pool their resources to track down the vaccine, and Doc enlists Jane as a nurse. Swearengen proudly collaborates on an article in the Deadwood Pioneer meant to minimize the threat of the outbreak.

After tracking down a murderer, Bullock returns to Deadwood a changed man as well as a marked one. Dan and Joanie both take a special interest when teenagers Miles and Flora Anderson arrive in camp in search of their father. Calamity Jane earns her moniker in the Pest Tent, while Swearengen sees through Trixie's subterfuge. Alma remains cold to Farnum's inappropriately advanced bid on her claim.

Deadwood breathes easier when some riders arrive in town with the smallpox vaccine, and word of a possible treaty with the Sioux. The results of Bullock's analysis of her gold claim move Alma to reassess her plans and sets up a confrontation between Bullock and Swearengen. When Flora tries to quit, Cy teaches Joanie a deadly lesson at the expense of a couple of con artists.

With annexation of Deadwood looming, Swearengen calls a meeting to set up an informal government. Bullock and Alma compare notes on Ellsworth and each other, and Farnum gets a special-delivery letter from Hickok and a special new post. Joanie finally prepares to make a go on her own, with Cy's avowed blessings, and after a long binge, Calamity Jane decides to ride out of town.

An opium theft leaves Swearengen trying to find a common language with his supplier, and navigating murky waters to deal with the mess. Meanwhile, Silas Adams, bagman for the magistrate from Yankton, arrives with bad news for Swearengen. Bullock regrets having raised his hand at the government meeting. An unwelcome and ailing Reverend Smith gravitates to the Gem and its new piano.

Alma's father, Otis Russell, arrives from New York to "help" with her claim. Swearengen strikes a bargain with Adams to rid him of some legal baggage involving the arriving magistrate. Jewel journeys to Doc's cabin for help with her leg. Eddie resumes work at the Bella Union, while Bullock is angered by the choice of the corrupt Con Stapleton as the new sheriff.

General Crook rolls into Deadwood with his troops, known as "Custer's avengers," and the Yankton magistrate, Clagett, prompting a parade and business solicitations from E.B. Farnum and Cy Tolliver. Al Swearengen delivers a tortured soul from suffering, and Bullock reacts decisively to Russell's intentions regarding Alma. Stapleton's new commission as sheriff proves short-lived, and Bullock and Alma have a late-night meeting.

Tensions flare as the camp faces an uncertain future. Al Swearengen taunts Seth Bullock over his relationship with Alma Garret, and the resulting confrontation between sheriff and criminal turns violent. With a new business venture on the horizon, Joanie Stubbs and Cy Tolliver await the arrival of some fancy new whores on the next stagecoach, which also bears two important reminders of Bullock's past.

Alma and an increasingly self-destructive Bullock face an abrupt decision on their future. At the Gem, while Swearengen readies for another showdown with Bullock, infighting between Silas Adams and Dan Dority yields more feed for Wu's pigs. Doc Cochran is surprised by Calamity Jane, who has returned to camp in a state of inebriated deterioration.

Francis Wolcott, chief scout for a powerful mining operation, arrives to shake up the status quo - beginning with Cy Tolliver. Swearengen's lackeys fret as he refuses visitors and medical attention. Joanie's new partner, Maddie, reveals she's also running a game as their new brothel, the Chez Ami, services its first customer.

Doc contemplates a procedure that could cure Swearengen - or kill him. Bullock attempts to settle into domesticity, while Sol gets a new student bookkeeper - Trixie. Alma cuts ties with Sofia's tutor, Miss Isringhausen. Joanie and Maddie argue over the business. The County Commissioner's arrival spawns rumors about the camp's future and legal ownership of the gold claims.

Swearengen is on the mend as Alma begins to take ill - mostly in the mornings. Cy is suspicious of Joanie and Maddie's operation, and makes an unexpected discovery about George Hearst's agent, Wolcott. Bullock attempts to control an outlaw mob and protect the Commissioner, who directed Merrick to print a provocative statement regarding gold claims.

Alma proposes opening a bank with the help of Sol Star. A new schoolteacher arrives in town, much to Merrick's delight. Much to Wu's dismay, new Chinese whores arrive. Wolcott's inner demons wreak havoc on Joanie's whorehouse, testing his alliance with Cy. Bullock attempts to keep order in the camp, and at the same time settle into family life.

Joanie discovers what happened at the Chez Ami and confides in Charlie Utter. Swearengen meets with Alma regarding Miss Isringhausen's allegations...and her connection to the Pinkertons. The town leaders convene to discuss pressing issues, but neglect to invite E.B., the mayor. By way of a strange circumstance, Utter comes into possession of Wild Bill's final correspondence.

Wolcott offers on the claim of two ornery brothers, and reports to Hearst on their progress overall. Miss Isgringhausen strikes a deal with Swearengen, who discusses his options with a friend in a small box. Alma receives very different proposals from both Mrs. Bullock and Ellsworth. A Russian telegraph operator arrives in camp, and Joanie befriends a reluctant Jane.

Bullock makes a connection with his son. Swearengen, who has entrusted E.B. to spy on the new telegraph operator, stokes rumors of an annexation of the camp and amends his agreement with Miss Isgringhausen. Cy aims to unburden a troubled man of his bloodstained money. Alma and Martha come to an agreement, and a tragic accident befalls the camp.

When Doc delivers a dire prognosis, one family suffers and the entire camp stands vigil. Merrick avails some private information to Swearengen, who enlists Star and Adams to help con the newly returned Commissioner Jarry. Andy, a former Deadwood pariah, offers himself as the camp's new minister. Trixie pressures a distraught Alma to accept a beneficial proposal.

Death in the camp spooks the superstitious, and the impending funeral causes much sorrow. Cy is convinced that Andy - who will officiate at the service - is back in town to run a game. Wu asks Swearengen to back him against the "San Francisco cocksucker". Bullock encourages his wife to stay in Deadwood.

A marriage occurs against a backdrop of murder and negotiations for elections and the camp.

Elections are just days away, and Bullock lets his temper get away from him. Alma's pregnancy is not progressing as expected, and Swearengen baits Hearst.

Campaign speeches are rescheduled, Sol makes an investment, Alma's condition worsens, and Hearst starts a deadly game with Swearengen.

A dandy arrives by stage coach and immediately begins exploring how to bring culture to the camp, Alma and Hearst negotiate business, and Hearst's Aunt Lou comes to camp.

Alma opens the doors to the new Bank of Deadwood and business is brisk. Hostetler return to Deadwood with the horse that killed Bullock's son. The Sheriff accepts that his son's death was due to an accident and blames no one. He finds himself acting as a go-between Hostetler and Steve, who has been taking care of the livery in Hostetler's absence and now feels he's being pushed out. Langrische makes an offer to buy Joanie's house with a view to opening a theater but Joanie imposes certain conditions before she sells. Hearst asks Cy Tolliver and Al Swearengen to a meeting to discuss business.

Tolliver looks for a representative, the Captain calls Dan out, Swearengen continues to be perplexed by Hearst's moves, and Alma and Ellsworth's relationship takes a turn.

Hearst's feathers are ruffled, Aunt Lou's son comes to town, and Bullock and Swearengen make a decision.

A meeting of the elders occurs with surprising results, Doc's absence is noted by Swearengen, Alma battles her addiction, and Sol offers Trixie something she never expected.

The letter is published, Wyatt Earp hits town, delays continue with the theater, and Hearst makes a move.

An Amateur Night is organized by the new theater troupe, Pinkertons hit town, the students move to their new school, and Hearst makes another move regarding the elections.

Swearengen is spurred to action when a prominent camp member is attacked, Langrishe makes arrangements for his theater, and Jane has an epiphany.

Another attack is made at Hearst's behest, Harry and Bullock travel to Sturgis for campaigning, and there's unrest in Langrishe's troupe.

Election day arrives, Hearst has his revenge, Sol and Trixie have it out, and Tolliver releases rage at his impotence.

Tolliver looks for a representative, the Captain calls Dan out, Swearengen continues to be perplexed by Hearst's moves, and Alma and Ellsworth's relationship takes a turn.

Doc contemplates a procedure that could cure Swearengen - or kill him. Bullock attempts to settle into domesticity, while Sol gets a new student bookkeeper - Trixie. Alma cuts ties with Sofia's tutor, Miss Isringhausen. Joanie and Maddie argue over the business. The County Commissioner's arrival spawns rumors about the camp's future and legal ownership of the gold claims.

Hearst's feathers are ruffled, Aunt Lou's son comes to town, and Bullock and Swearengen make a decision.

Competition arrives for Swearengen in the form of the Bella Union, a new gambling outfit from Chicago operated by savvy Cy Tolliver, Madame Joanie Stubbs and gaming guru Eddie Sawyer. Hickok puts up precious collateral in a poker game with McCall; Bullock and Sol strike a deal with Swearengen on a lot for their hardware store. Garret threatens Swearengen before investigating his gold claim.

After tracking down a murderer, Bullock returns to Deadwood a changed man as well as a marked one. Dan and Joanie both take a special interest when teenagers Miles and Flora Anderson arrive in camp in search of their father. Calamity Jane earns her moniker in the Pest Tent, while Swearengen sees through Trixie's subterfuge. Alma remains cold to Farnum's inappropriately advanced bid on her claim.

Francis Wolcott, chief scout for a powerful mining operation, arrives to shake up the status quo - beginning with Cy Tolliver. Swearengen's lackeys fret as he refuses visitors and medical attention. Joanie's new partner, Maddie, reveals she's also running a game as their new brothel, the Chez Ami, services its first customer.

When Doc delivers a dire prognosis, one family suffers and the entire camp stands vigil. Merrick avails some private information to Swearengen, who enlists Star and Adams to help con the newly returned Commissioner Jarry. Andy, a former Deadwood pariah, offers himself as the camp's new minister. Trixie pressures a distraught Alma to accept a beneficial proposal.