The Lord of Lost Causes by Kate Pearce

Struggling to support her family after her husband’s death, Caroline Harding attracts the attention of the ruthless Captain Francis Grafton who offers her a devil’s bargain to pay back her debts to him. Outwitting her enigmatic employer and unwillingly gaining his approval significantly changes her life for the better, but can she win his loyalty and his heart when he appears to care for nothing but profit?