An Unfamiliar Duke by Sian Ann Bessey

​​At eleven years of age, Rosalind Ainsworth was convinced that Sebastian Lumley, the future Duke of Kelbrook, was the most odious young man she’d ever met. And ten years later, after having had no contact with the nobleman in the intervening time, her opinion of him has not changed. Unfortunately, neither has the marriage contract their fathers signed soon after her birth.
As Rosalind’s twenty-first birthday and the appointed wedding day approaches, Sebastian makes a rare appearance in London. His first meeting with Rosalind since childhood goes less than perfectly, but Sebastian has a compelling reason for honoring their marriage contract—a reason outlined in a document kept behind his workshop’s locked door.
After a quick wedding, the new couple relocates to Finley Park, where their acquaintanceship slowly blossoms into affection. But when Sebastian’s secretive work threatens their fledgling relationship and Rosalind’s life is placed in jeopardy, Sebastian finds himself forced to choose between the man he has pledged to help and the woman he has come to love.