The plot concerns two – literally starcrossed – lovers: Swithin St. Cleeve, a very young amateur astronomer, and Lady Viviette Constantine, an unhappily married and abandoned woman ten years his senior. Each night Swithin climbs the old tower of the title, in the grounds of the Constantine estate. Lady Constantine, whose husband has been absent some years on an extended hunting and exploring journey to Africa, joins the young man in his stargazing, and supports his astronomical ambitions by buying him equipment, though his dreams of scientific renown are disappointed. The couple marry in secret, after having been told of Mr. Constantine’s death in Africa. They discover to their horror that the wedding is formally bigamous, as he was still alive at the time of the vows, but maintain the secret to preserve a legacy to Swithin. He goes abroad to pursue his studies, but unknown to both of them leaves her pregnant; to avoid giving birth to an illegitimate child she weds an aging bishop, who also soon dies. On his return, Swithin neglects Viviette and their son in favour of Tabitha Lark, a local organist. In a melodramatic finale, Swithin finds Viviette and their child atop the tower, and offers to wed her, but the shock is too much for her overtaxed heart, and, as Tabitha Lark approaches below, she falls dead. Wimborne was the location of the village of “Warborne”, and Charborough House was the location of the “Welland House” in Two on a Tower.