Rich, powerful, dangerous, eccentric. A lady couldn't be seen with them without ruin. Rumors surround them--of tragic violence, of their mistresses, of their dark appetites, of scandals that set Victorian England and Scotland abuzz. Hart, Cam, Mac, and Ian: each a tortured genius, each ready for love and darkly sensual games.

This series, set in England and Scotland in the 1880s, presents the romances and adventures of the Mackenzie clan. Each book stands alone, but they are most enjoyable when read in order. 

http://www.jenniferashley.com/jennifer-ashley-books/highland-pleasures/mackenzies-series-chronology-and-reading-order/