When Lady Emily Fairfax comes face-to-face with a girl who looks just like her, she thinks that she has seen a ghost! It soon becomes clear, however, that Miss Ava Smith is no ghost, but is actually Emily’s long-lost twin sister.

Desperate to extricate herself from a loveless arranged marriage, Emily persuades her twin to swap places with her for a month. The plan is for Ava to stay in London and scupper Emily's engagement, whilst Emily takes Ava's place as a governess in Kent.

It seemed like the perfect plan, until Emily comes face-to-face with her new employer, the devilishly handsome Duke of Hemsworth - the ton’s most notorious rake. After the death of his best friend Lord Dunstable, Robert Charles Adrian De Lacey, Sixth Duke of Hemsworth had found himself with two wards. Determined to do right by them, Rob vows to leave his life of debauchery in London behind - a vow which is quickly challenged by the arrival of the children’s beguiling new governess Miss Ava Smith.

Knowing that he can never make a commoner his bride, Rob tries to push his attraction for Miss Smith aside, but despite his best efforts, sparks soon begin to fly between the pair. Their burgeoning romance is dramatically interrupted, however, when it becomes clear that a mysterious someone is seeking to hurt both Rob and the children.

Can Rob discover who the villain is, before they harm his wards? Moreover, can he resist his enchanting governess?