Kathryn Caskie delights with the third book in her "Seven Deadly Sins" series, entitled The Duke's Night of Sin. As the daughter of a duke, Lady Siusan Sinclair feels it is her right to spend life doing nothing but those things expected of a lady - knitting, serving tea, and flirting with her fan - but when she encounters pleasure in the arms of the Duke of Exeter one night, she knows she must flee London or else face the wrath of her father.

Upon the death of his older brother, Sebastian Beaufort is made into Lord Wentworth, Duke of Exeter, a role he fears since the last two dukes met untimely ends thanks to their wild ways. Sebastian thought his own wild days were behind him, until he makes love to a sinful creature right in his library during his gala. Before he can learn her name, she flees from his sight. Intent upon finding her, the Duke of Exeter combs London and attends countless balls in hopes of seeing a girl wearing a blue gown, for that is all he noticed of her - that and her vibrant midnight hair.

Siusan has been labeled one of the seven sins by none other than her father: her vice is sloth. Trying to change her father’s opinion and escaping the clutches of the Duke, Siusan runs off to be made a teacher at Mrs. Huddleston’s School of Virtues as a Miss Suisan Bonnet, but it is no use trying to hide from fate: Sebastian’s ward and niece is one of Suisan’s students.

Sebastian and Suisan are thrown together time and again; they profess their love for one another yet cannot marry because of Suisan being one of the seven sins. Eventually, though, Sebastian realizes that his love for Suisan outweighs society’s opinion.

It's difficult to understand why their alcoholic father could label his children as sins, or why Suisan and her siblings even care what their alcoholic father thinks even though he held the purse strings. Perhaps reading both Sterling and Ivy’s previous stories would illuminate the matter. Although the plot could have used a little more work, the love story is delicious.