The novel "Rob Roy" gives a broad and complex picture of Scottish and English public relations at the beginning of the 18th century. The action develops quickly, more lively than in other Walter Scott novels. The main character, Francis Osbaldiston, is suddenly recalled from Bordeaux to his father on an important matter. Arriving in London, a twenty-year-old man learns that his father wants to entrust him with the affairs of the Osbaldiston and Tresham trading house, of which he is the director. Osbaldiston Sr. realizes that years or a sudden illness will one day overwhelm his strong body, and he seeks to prepare in advance an assistant in the person of his son, who will take the wheel from him when his hand weakens, and will lead the ship according to the advice and instructions of the old captain. But Frank has no desire to comprehend the secrets of commerce, this is an artistic nature, he writes poetry, loves literature. His refusal leads his father to indignation, our hero is in danger of losing his inheritance, but this does not frighten him, and Frank throws to Owen, the company's senior clerk, the phrase: "I will never sell my freedom for gold." Father punishes Francis to the north of England, to visit his uncle there and meet his family, with whom he himself does not maintain any relationship. One of the uncle's sons will, according to the design of Osbaldiston Sr., take Frank's place in the trading house.

Francis sets off on a trip to a hotel and meets Mr. Campbell, a Scottish-born man, who becomes the soul of the company and arouses universal interest. But the paths of Campbell and Frank diverge.

So, the young man arrives at his uncle’s castle, Osbaldiston Hall, a stronghold towering above the forests and cliffs of Northumberland - the border area, behind which romantic Scotland, unknown to Frank, begins. The family portrait of the inhabitants of the castle is devoid of romance. “Not a bad collection,” Frank notes after meeting six cousins ​​— drunkards, gluttons, and loafers. Only one of them stands out from the general series - Rushley, the younger Osbaldiston; it is he, as we later find out, who should take the place of Frank. In the castle lives a distant relative of her uncle, Miss Diana Vernon, a beautiful, intelligent and educated girl. Frank is fascinated by her, he hears her every word, listens to the accurate psychological characteristics that she gives to the inhabitants of the castle; her speech miraculously combines insight, courage and frankness.

The measured, boring life in the castle suddenly ends. Frank is accused of high treason - such news reports Diana. Morris, one of Frank's companions on the road, was robbed and suspects him of his deed; due to the fact that Morris was taking money from the Treasury to pay troops in Scotland and he had stolen very important documents from him, this is not about simple robbery, but about high treason. Diana offers Frank her help and wants to transport him to Scotland. (“No one will intercede for you, you are a stranger; but here, on the outskirts of the kingdom, local courts sometimes do ridiculous things.”) But Frank objects: he is not to blame, so you need to go to court and restore justice. Mr. Campbell suddenly appears in the judge’s house, exposing Morris, revealing him in a lie. It turns out that Campbell accompanied Morris on the road and was a witness to the incident; he outlined a picture of events, and the audience learned that Morris was terribly chickened and did not even try to resist the robbers, although he was in the army of His Majesty, and there were only two robbers. Campbell remarked to himself that he was distinguished by a peaceful disposition and never interferes in quarrels and fights. Frank, who was listening carefully to Campbell's story, caught the discrepancy between the words and the expression on his face when he spoke of his peacefulness, and suspected that Campbell was involved in the incident by no means as a companion of Morris, who was injured with him, and not even as a spectator. But it is thanks to Campbell that the slanderer and coward Mor-rice is ready to give up his testimony against Mr. Osbaldiston. The court case is closed, Frank is beyond suspicion.

However, this story is only the beginning of the trials that befell our hero. From Raschley, Frank learns Diana's secret: according to an agreement concluded between the families, she must either marry one of Frank's cousins, or go to the monastery. Frank in love falls into despair. Diana warns him of a new danger: Frank's father left for the Netherlands on urgent matters, and entrusted Racheley with managing the company in his absence; which, in her opinion, will lead to the ruin of his father, since he wants to use the income and property of Osbaldiston Sr. as a means to the realization of his ambitious and insidious plans. Miss Vernon, alas, turns out to be right: Frank soon receives a letter from his father’s companion, who asks him to immediately go to the Scottish city of Glasgow, where Rashley is probably hiding with a large amount of stolen money and bills, Frank needs to meet with Owen, who already went to Glasgow. The young man is saddened by parting with Diana, but he understands that for his father, “bankruptcy will be the greatest, indelible disgrace, grief for which the only healing is death”; therefore, having taken the Scottish gardener as a guide, he gets to the city by the shortest route.

During a service in a church, a stranger makes an appointment for Frank, adding: “You are in danger in this city.” He leads Osbaldiston to prison, in Owen’s cell, where this hardworking and devoted man tells his father the following. In Glasgow, the trading house had two main partners: the obligatory and compliant McWittie and the stubborn, intractable Jarvey. Therefore, when Owen, arriving in Scotland, turned to McWittie for help in a difficult moment for the company, he hoped for support, but his request was rejected; moreover, the “reliable” companion demanded that the entire cash asset of the company be handed over to him as a guarantee in the event of a collapse. Owen indignantly rejected this demand and ended up in prison as a debtor, Frank realized that the warning he received meant that he himself could be imprisoned if he openly defends Owen, as Scottish debt laws are mercilessly harsh. Suddenly, Mr. Jarvey, an alderman (senior member of the city council), appears in prison, who, having learned about the troubles of Osbaldiston and Tresham, came to the rescue. He gives a guarantee, and Owen is free. During this meeting, we learn that the alderman and the mysterious stranger who brought Frank on a date with Owen are relatives. A startled Jarvey exclaims: “You, a notorious lawless person, did you dare to crawl here to the Glasgow prison? “Robber, robber, how much do you think your head is worth ?!” But Frank's conductor, whose name is Robin, is unperturbed, he replies to his cousin: "We, the highlanders, are stubborn people." What amazed Frank, when he suddenly realized: the stranger Robin and Mr. Campbell - one face! And again this extraordinary man offers his help. Robin advises: let Owen stay in Glasgow and do everything he can, and Frank, meanwhile, will go the next morning, accompanied by Jarvey, who knows the way, to him (Robin) in the mountains.

In the evening, walking in a city park, our hero meets a strange trinity: Rushley, McVitti and Morris. They do not notice Frank, are having a conversation, and he waits until Rushley is left alone. A duel on the swords of two enemies could lead to a tragic outcome, but the timely appearance of Robin stops the bloodshed.

Frank, on the eve of his departure to the Highlands, asks Jarvey to tell about her customs, and the alderman willingly describes this corner of Scotland. This is a very special, wild world with its own laws. Half of the adult population is unemployed, and they live by theft, robbery, and cattle theft, and, worst of all, they are proud of it. (“They do not know any other law than the length of their blade.”) Each laird contains a small army of such robbers, called the clan, and since 1689 peace in the mountains has been supported by money, which, by the king’s order, the lairds handed out to their daredevils. But now, from the time of King George’s accession to the throne, the order is different: they don’t give out money anymore, the leaders don’t have money to support the clans that eat them, and, most likely, an uprising will soon break out. This event can accelerate Rushley. Osbaldiston Sr. bought up forests in Scotland, and the trading house paid in large bills; and since the credit of the company was high, the gentlemen of the Mountain Country, holders of bills, always received loans in Glasgow for the entire amount indicated on the bills. Now, if the bills are not paid, the Glasgow merchants will rush into the mountains to the lords, who have almost no money, and will begin to draw veins from them, leading them to despair, so that the termination of payments by the trading house of Father Frank will accelerate the explosion, long overdue. “How strange,” Frank remarked, “that the trading affairs of London merchants influence the course of the revolution and uprisings.” What can Robin do in this situation, and why did he call Frank to the Mountain Country? Alderman advises Frank to rely on Robin.

Finding Rob Roy (this is what Robin was called for his red hair) in the mountains is not easy at all, the captain of the royal army Thornton was ordered to catch Rob the robber as soon as possible, and despite the mountaineers disarming the military detachment, which was three times their strength, Rob Roy is still captured. When crossing the river, he manages to escape thanks to the help of friends. At night in the mountains, the pathways of Frank and Rob Roy converge. Rob Roy brings Frank and Jarvey to his home, and Frank listens with interest to the story of this amazing person. Once Robin was prosperous and hardworking, but difficult times came, and Rob loved to take risks and as a result turned out to be a bankrupt, a barefoot tramp, deprived of his entire fortune. There was no help from nowhere - "there is no shelter or protection anywhere," - then Rob Roy leaned into the mountains, began to live "his own law." Farmers paid him a "black tribute"; this money served as a guarantee that their property is inviolable: if, for example, thieves take away even one sheep, Rob must return it or reimburse its value. And he always kept his word. Soon, Rob Roy rallied a whole team of daredevils around him and became their favorite leader, a man whose one name filled with fear. Robin had long guessed about Rashley’s vile intentions and now forces him to return all bills and securities by means of threats in order to immediately transfer them to Frank. Our hero is once again convinced that this "robber" is a magnanimous, honest person who does not want to part with.

In Glasgow, Frank meets with his father, who managed to settle all cases and sue Rushley. But the trial will never take place, since a rebellion breaks out in the mountains just before the Osbaldistons leave for England. Frank in the ranks of the royal troops is involved in his suppression. During the fighting, all of Frank's cousins ​​who lived in Osbaldiston Hall die, and Frank remains the only heir to the castle. But he does not want to live alone and goes in search of Diana Verna. The girl, meanwhile, fulfilling the will of her father, is in the monastery. There Frank finds her before she manages to get a haircut as a nun. They marry and live in the castle happily ever after.

And in his native country still lives the memory of Rob Roy as a Scottish Robin Hood.