The Mystery of Mr Daventry by Adele Clee

A gentleman who hides many secrets.
Society thinks it has the measure of Lucius Daventry, illegitimate son of the Duke of Melverley, but they know nothing of the dangerous man who lies beneath the constructed façade. As a member of a secret group known as the Order of Themis, he works to right injustices, to make wicked men pay. But someone is seeking revenge on its members, resulting in the murder of their leader, Atticus Atwood, and Lucius will stop at nothing to find the person responsible.

A lady with secrets of her own.
Sybil Atwood still grieves the loss of her beloved father and has focused her attention on seeing the return of his personal journals and scientific artefacts. What possessed Atticus Atwood to bequeath his life’s work to a man like Lucius Daventry is a mystery. Indeed, the dissolute rake is far removed from Atticus’ usual associates. But having received threatening letters demanding she gain possession of the journals or face dire consequences, Sybil has no choice but to approach the devilish Mr Daventry.

A clash of personalities brings about surprising rewards.
Thrown together by a twist of fate, Lucius and Sybil become involved in murderous plots, secret societies and a race to catch an evil villain. In a wild adventure that takes them to the dark depths of London’s underworld, they find they’re inexplicably drawn to one another. Both are compelled by a powerful attraction. Can Lucius overcome his demons and open his heart to the possibility of love? Will Sybil learn to trust a man with such a scandalous reputation?