Walter Methven is an indolent young man of twenty-four. To the despair of his widowed mother, he prefers a circle of friends led by the shifty Captain Underwood to the regular pleasant society of their town. It is known that Walter is a distant relation of the Scottish Lord Erradeen; but it comes as a shock to him and his mother to learn that due to several deaths in the family, he has succeeded to the title. He vows to put aside his aimless past and do some real good in his new position. Walter travels to Edinburgh to meet his solicitor, and learns that one of the conditions of bearing the title is to spend several days each year on Loch Houran in the West Highlands, at the ancient castle of Kinloch Houran. Centuries ago there was a Warlock Lord of Erradeen, an evil man who seemed to have the powers of the Devil; and some believe that he still exerts his power over each Lord Erradeen in turn. As this sinister figure begins to haunt and influence Walter after his arrival at Kinloch Houran, he reaches out to two ladies on a nearby island, Mrs Forrester and her daughter Oona. Once Walter leaves the Highlands he all too easily falls into bad company again, yet at times struggles to rise higher. Before this supernatural tale ends he will again return to Kinloch Houran; and there will be a final moral struggle between good and evil, leading to a dramatic ending.