Having won a saloon, Bart arrives in town to find it closed because of a competing claim of ownership by the Marquessa, the alleged heir to the land grant on which the saloon and the town sits. Bart suspects that the Marquessa is a fraud, but is she?
Having been tricked into buying a share of a steamboat instead of the whole boat, Bret and his co-owners sail the boat up the Mississippi to an interested purchaser. Along the way, however, the co-owners start dying one by one.
Bret and Bart are hired by the feuding Carteret and Montgomery families to settle a longtime dispute by a poker competition. The families are unaware of Bret and Bart's relationship, but when they become suspicious the stakes are considerably raised for the brothers.
A big winner at poker, Bart puts his winnings in the hotel safe. When he awakes, his cash is gone and the clerk is dead. His only chance for a stake is the bank president, aka the Widow White, whose future is threatened by mysterious notes.
Finding himself in love with a woman who disappears, Bret follows her trail to Guatemala City. There he finds her, but she is living under another name. While trying to find out why, Bret must also deal with the adoration and shenanigans of a young street urchin.
Bart thwarts an assassination attempt on a local politician. With the wounded man unable to run for election, Bart is drafted to take his place on the ballot as a candidate for the Reform Party, a matter not looked on with favor by the competing politician behind the assassination attempt.
Losing the last few dollars in a poker game, Bart goes after some seemingly easy money for him and his friends. He thinks he can insure a cattle drive and meets a man who looks familiar but can't place his face - soon he does his hand.
Arriving in a town for the first time, Bret finds himself accused of swindling the town folk and killing its mayor. And his only chance of escaping the noose appears to rest with a scheming Melanie Blake and a superstitious lawyer new to the town.
Foursquare Farley has discovered a unique way of obtaining a bank loan - a secret tunnel to the Bank of Denver's vault. But with a safe cracker planning to break into the vault, Foursquare and Bret fear that the tunnel will be discovered and Foursquare blamed for the impending robbery. The result is a cat-and-mouse game of now you see it, now you don't.
Returning to America after an extended stay in England, Cousin Beau Maverick is hired to take the place of a young English nobleman. However, he soon finds himself the victim of a kidnap and ransom plot due to his assumed identity.
Bart is framed for several crimes by crooked Sheriff Hadley and his deputy, who force him to take part in their racket--hunting down and killing innocent men, then claiming they're outlaws and collecting the reward. Bart turns bounty hunter in an effort to expose the corrupt lawmen's scheme and asks for help from several of his friends (all of whom are stars of other contemporary Warner Bros. TV western series, making cameo appearances).
Beau can't win for losing - sashays up to claim a worthless mine he won, then the whole town disappears. The no-longer Silver Hill stands at the mercy of the venal Wilber Shanks, a sanctimonious railroad land buyer, whose threat to divert his rail line far from Silver Hill forces its befuddled citizens to immediately take Shanks' mare to chat up a lonely bachelor sheep rancher who's desperate for some 2-legged company for a change.
Left in the desert to die, Bart - actually just his fine mane - fascinates Red Feather who's on a walkabout of sorts. Captain/First Mate Jim of a passing prisoner wagon train saves Bart's scalp, plus the train stars luscious murderer Daphne, who's delighted with Bart as the hearty First Mate's Gilligan. But as the cruise of the Arizona Black Maria nears the penitentiary, wily crooks Dishonest Abe and Fingers Louie aren't so taken with pal Bart.
Beau & Bart fight to escape a black hole - where money and people enter, but can't leave! The cousins have to sleep sitting up in Stop Gap's only watering hole, after saving from robbers the treacherous Wembly, who promised them free, comfy hotel beds - but knew the inn was full-up. Wembly's suspiciously tight with the mining town's telegraph owner, son of a Colorado Senator. Why is the town too small to have a bank, as its population and wealth mysteriously expand to infinity - and beyond?
Accused of murdering his partner in a casino, Beau tracks a saloon singer who can clear him to a small town where she's now working as a teacher--with the murdered man's trigger-happy brother and a sheriff on Beau's trail.
Bart howls like a hound dog when an alluring witch ravels him in great Smoky Mountain feud-in, fight-in and spell-in. Riding to Hound Dog, Tennessee to collect a debt from High Card Harris, Bart ignored a raven perched on a road sign, who the banshee insists is her dead Pappy. Bart shrugs off the witch's forebodings, then sees the Southern Hamlet disintegrate when he gives the raven-haired enchantress a lift in. Bart's own Pappy never told him there'd be days like this, much worse nights.
Beau finds himself used as a scapegoat by two shopkeepers who killed the son of the chief in an effort to hide their swindle of local Indians. Captured by the Indians, Beau faces a death sentence only to be spared by the chief's daughter who claims Beau as her future husband. But Beau finds that his reprieve is only temporary until the honeymoon is over.
In Bret's last episode, the Maverick brothers (Bret and Bart) find themselves the heirs to a stagecoach line. Thinking they have struck it rich, they find instead that the stagecoach line is broke. But the railroad is coming through and the stagecoach's right of way might yet provide their fortune, or so the brothers hope.
Beau and an old man riding with him are both captured and accused of being horse thieves, in Beau's case, one Benson January. Despite the efforts of a young lawyer (who may or may not be Tom Brewster), Beau is sentenced to hang. His fate may depend on a young woman - the sister of the girl January was engaged to. But will she be willing to help?
An eccentric woman hires Beau to be her bodyguard and claims she has been subject to repeated threats. But every time she claims there has been a threat, there is no evidence to support the allegation. The woman's family claims the alleged threats are part of her mental delusions and take steps to have a court declare her incompetent with control of the woman's fortune to be placed in the hands of others. Nobody believes the woman's claims. That is, nobody but Maverick.
On his way to the bank to collect a gambling debt, Bart rescues a petulant young woman from a runaway horse. On returning to the bank, Bart and the woman find that the bank president has absconded with all the money, including the money to pay Bart's debt and all of the woman's money from sale of her land. The woman hires Bart to get her to Dodge City with the promise that her fiancé will pay him when they arrive. So they set out essentially penniless for Dodge city, only to later find that they are being tracked by a ruthless bounty hunter because they are now wanted...
Mistaken at a convention hotel to be Beau O'Maverick, Beau is recruited by the army to infiltrate a group of Irishmen in order to find out why they are massing near the Canadian border. But if he is discovered as a spy, it could mean facing a firing squad.
Freeloading a train ride to Denver, Bart makes it as far as Crenshaw where he meets an old friend. When he finds how he figures prominently in her plans to take a lot of gold to Devil's Flats, he may wish he should have stayed on that train.