War on the Highlander’s Heart by Maddie MacKenna

Either a secret or a sin, she was his to hold, forever…

Lady Penelope Warren firmly believes there is nothing worse than living with parents that hate you. That is until the day she learns that she is to marry a Laird she despises.
When a fire destroys half his Castle, Rodrick Finterson, Laird of Durmont, realizes that he has but one choice if he is to save his clan from annihilation: accept an arranged marriage to a loathed but inexplicably bewitching Sassenach.
With more and more skirmishes breaking out at the border, their budding flame is put to the test. On the way to a neighboring clan to form an alliance, an ambush rains steel and fire on Rodrick’s party. But a single realization makes his blood run cold. The ambush is but a diversion and the enemy means to destroy him from within. Starting with Penelope…