The X Bar X boys ride into Eagles to meet their father, who is arriving by train after a week in "the city." They are bringing his horse, General. When they greet their father at the station, he introduces them to Nell and Ethel, whom he has met on the train and who are coming from New York to visit the neighboring 8 X 8 ranch. While they are talking, the boys' horses Flash and Star, along with General, are stolen. Gilly Froud, a former ranch hand on the X Bar X who had been fired for mistreating Flash, is suspected of the theft, along with a band of ne'er-do-wells he has gathered around him. When local ranches begin to lose cattle in large numbers, it is time for the X Bar X-ers to put an end to it.

A pompous easterner, acting on behalf of a conglomerate, makes an outrageously high offer for some of Bardwell Manley's prime cattle. Although noting that the man knows next-to-nothing about cattle, Mr. Manley nevertheless agrees to sell. It is curious, however, that the buyer insists on an unusual forfeiture section in the contract, and that the cattle be rounded up and delivered to a little-known and scarcely-used railway depot. A humorous incident involving a fortune-teller, several truly gratifying family scenes, and the action-packed conclusion make this a well-crafted book.

When the boys find an old miner who had been shot and left for dead, they bring him to the ranch for some tender loving care. When the old man is able to speak, he announces that he was robbed of about $20,000 in gold; at about the same time, news arrives of a major gold strike at nearby Nugget Camp. The ensuing gold rush causes many of the ranch hands to leave the X Bar X and other ranches for the site. The boys decide to join the rush and try to strike it rich while they look for the old miner's assailants and attempt to recover his nuggets.

The few rustlers who escaped being captured at the end of the previous book come together and set out to exact revenge. Being slow learners, they cut a good number of cattle from the X Bar X herd, and head for the hills. The ranchers organize once again to track and foil the rustlers. In a subplot, the three girls, who are traveling to New York where Nell and Ethel come from, are among the passengers on a train which is stopped and robbed by masked men. The descriptions of blizzards are splendidly written. The conclusion is set in the wilds of Grizzly Pass.