The five richest men in the territory gather in Laredo for their annual high-stakes poker game. The high rollers let nothing get in the way of their yearly showdown. When undertaker Tropp calls for them in his horse-drawn hearse, cattleman Henry Drummond forces a postponement of his daughter's wedding, while lawyer Otto Habershaw abandons his closing arguments in a trial, with his client's life hanging in the balance. They are joined by Wilcox and Buford in the back room of Sam's saloon, while the curious gather outside for occasional reports. Settler Meredith, his wife Mary, and their young son Jackie are passing through, on their way to purchase a farm near San Antonio, when a wheel on their wagon breaks. They wait at Sam's while the local blacksmith repairs it. Meredith, a recovering gambler, learns of the big poker game and begins to feel the excitement once again. The newcomer buys into the game, eventually staking all of the family savings, meant to pay for a home. The game builds to a climactic hand; the gamblers raise and re-raise until more than $20,000 is in the pot. Meredith, out of cash, is unable to call the latest raise. Under the strain, he collapses. The town physician, Joseph "Doc" Scully, is called to care for the stricken man. Barely conscious, Meredith signals for his wife to play out the hand. Taking his seat, Mary asks, "How do you play this game?" At this, the other players object loudly, but eventually give in. The situation is explained to her: if she cannot match the last raise, she will be out of the hand. Despite the men's protests, she leaves the room to borrow additional funds. With Jackie and four of the players trailing behind, Mary crosses the street and talks to the owner of the Cattle and Merchants' Bank, C. P. Ballinger. After she shows him her hand, Ballinger suggests she is playing a practical joke. When he is told otherwise, he loans her $5,500 and makes a $5,000 raise for her. The other players, aware of Ballinger's tightfisted, cautious nature, all reluctantly fold. Mary collects her sizable winnings and pays Ballinger back with interest. The game then breaks up, no one ever having seen the winning hand. The lady's determination earns her the admiration of the men. Drummond is so touched that, when he returns home to the waiting wedding ceremony, he talks privately to his weak-willed, prospective son-in-law, gives him some money, and orders him to run away and find himself a better wife than his daughter. Later, it is revealed that Meredith, Mary, and even their "son" are confidence tricksters and expert card sharps. Together with Ballinger and Scully, they have perpetrated a scam on the other poker players, who had swindled the banker in a real estate deal sixteen years before. "Mary" is actually Ballinger's girlfriend Ruby. She had promised him she would give up gambling after the caper, but she sits down to another poker game, much to Ballinger's dismay.
