Set in the closing years of the 19th century, this two-part novel tells the story of Lewis Haystoun, a young Scottish laird. Part I of the novel is a story of manners and romance in upper class Scotland. Part II is quite different, and is an action tale of adventure and duty in northern India.
When his local Member of Parliament decides to retire, Haystoun is persuaded to stand. Although he is liked and respected by his local tenants, he finds himself unable to speak wholeheartedly and with full conviction at the hustings and is beaten by his opponent, the ambitious and fluent social climber Albert Stocks. Following an initial meeting at a dinner party, both Haystoun and Stocks fall in love with Alice Wishart, the daughter of a rich city merchant. Miss Wishart initially favours Haystoun, but gradually becomes disenchanted with his apparent lack of ability to commit to anything. During a picnic on the moors, Miss Wishart slips and falls into a lake. Haystoun, standing beside her, hesitates just long enough to allow his rival to dive in and make the rescue. Haystoun is devastated, believes himself to be a coward and avoids Miss Wishart's company, pushing her more and more into the company of Stocks. Stocks asks her to marry him and, believing that Haystoun is not interested in her, she agrees.
Rumours have reached the British Government of a possible danger to the Empire via an uncharted area of the northern Indian frontier. Haystoun has explored this area before, and when he is asked by a friend to go out again to reconnoitre in a semi-official capacity, he jumps at the chance to escape his situation and to prove his courage. The night before his departure, Haystoun and Miss Wishart meet and declare their mutual love for the first time. Although there would still be time for Miss Wishart to break her engagement, the pair feel that they have been 'set apart by the fates' and they separate to follow their own individual paths.
In part II of the novel, Haystoun travels to the northern frontier lands where he learns of a Russian plot to invade India via a little-known narrow mountain pass in the Kashmir, with the help of the local hill tribes. Having become aware of an imminent Cossack attack, Haystoun sends word to the local fort, calling on them to telegraph warnings to the northern garrisons and settlements, and sets off alone to try to delay the invaders at the pass. There he dies heroically, but is able to delay the invasion for just time enough for the alarm to be raised and for defences to be put in place. The Empire is saved by his valiant efforts.

Question: Why is Haystoun asked to go on this mission?
Answer: He has experience in this area.
Alternative answer: Because there is a rumor of a threat to the Empire