Naughty Irish Heart by Abby Knox

The Year 1871: Stable boy Will O’Leary has simple goal: keep his head down, work hard, take care of his ailing mother, and maybe make a happy life for himself in his newly adopted country. But his employer’s eldest daughter Annie Fitzpatrick threatens to muck things up by taking up too much space in his mind, with her carefree ways and flame-red hair. If they don’t give in to their burning desires soon, their passions might just set the whole city on fire.
Present Day: Bar owner Emmett O’Leary believes he’s the direct descendent of the family whose cow kicked over a lantern and started the Great Chicago Fire of 1871. In fact, he earns a decent living for himself off of his associations with that tall tale. When a historical researcher and familiar face from the past, Iona Kelly, shows up in time to rain on his parade shortly before Saint Patrick’s Day, her well-meaning ways upend his entire life.