After schoolteacher Abbott breaks the windows in Mawson's saloon because it is too near the school, Dink Davis' henchmen hold her hostage in Mawson's cabin to frame Mawson as means to remove him as a competitor.
California, at a will reading, learns he shares with six others an inheritance in which the survivors share equally as any of the others die and murder ensues so Hoppy begins an investigation despite being told the estate is worthless.
Needing supplies Hoppy and gang go to Mesa City and find a big celebration about an irrigation project and that the project promoter is a crook but not before California is blamed for bank robbery because of a switch with the robbers.
At the request of an army officer friend, Hoppy goes to retrieve the officer's deserter son from an outlaw enclave where he learns the son is being forced by the ringleader to take part in scam to take gold in cavalry disguise.
Hoppy helps an archaeologist friend pursue an expedition by promising the area tribe that there will be no looting of burial places but for gold an expedition member betrays them with a gang that rustles castle disguised as tribe members.
Hoppy's gang takes refuge from a storm in a deserted church; in the middle of the night they find playing the organ a daughter of the deceased pastor who is almost killed by a falling beam and find oddly in the morning a wrecking crew.
Hoppy and California must avoid angry, suspecting ranchers to find Lucky who has been hypnotized by snake oil salesman Doc Richards to deliver to him the proceeds of the Cattleman's Association sale made by Hoppy.
Hoppy and Red find a severely wounded man who mentions the name of neighboring ranch owner in his dying breath. Hoppy decides to investigate and finds the murdered man and the nearby rancher had been engaged in a on-going fight over water rights that sometimes led to bloodshed. When Hoppy meets the accused rancher's lovely young wife, he isn't so sure that the man isn't being framed for the murder.
A boy asks Hoppy to investigate the death of his father who was killed after being accused of cheating at cards. At first Hoppy can't find a motive for the crime, but when the boys mother dies under mysterious circumstances, he begins to suspect the boy's legal guardian of plotting the murder.
An Indian agent asks Hoppy to help persuade an Indian chief to reveal the location where crude oil can be found on the land's surface. The country will be opened to settlement and unless the tribe agrees to contract with oil companies before homestead claims can be filed, an outsider might grab the land and prevent the Indians from earning income from the oil wells.
Red uses $1000 of Hoppy's money to invest in scrub land, because he hears of an irrigation ditch being dug to bring water to the worthless tract. Cassidy investigates and learns that the developer is using Hoppy's name to promote the swindle.
The U.S. Army asks Hoppy to investigate when a herd of horses desperately needed for the Spanish-American War is stolen from the ranch who was supposed to supply the herd. The ranch workers insist the horses were rustled by Mexican bandits, but the Mexican authorities claim that no herd of horses crossed the U.S.-Mexican border, legal or illegal.
The Twin Forks ranchers are looking forward to a good year with plentiful rainwater and lush grass to fill their cattle's bellies until a sheepherder threatens to move his stock onto the range to compete for forage. Hoppy must work fast to prevent a range war between the cattlemen's association and the interlopers.
While searching for a missing calf, Hoppy and Red are shot at from ambush. They quickly capture the would-be drygulchers, who turn out to be a couple of hungry kids riding cross-country to claim their inheritance. Hoppy isn't too concerned about the misunderstanding - the youths paid for the calf, after all - until he learns that the money he was paid with is counterfeit.