I read this book over 25 years ago as a teenager and still remember it quite vividly.
Another reviewer, 'Tasha', quite rightly describes it as not one of Buchan's best novels, but its themes of love, cowardice and redemption really resonated with the shy young man I was at the time. The first half of the book, which is set in the highlands of Scotland, is much the best and describes how a privileged but shallow young man loses the love of his life through caution and weakness of character. In the second half of the book - set in India, but not as well written - he redeems himself through brave and sacrificial service to his country. Obviously these themes are highly unfashionable these days, but it made me think a lot about the nature of honor and courage, and of the need to take the tides of life at the flood.