Once Upon A Scot by Cynthia Luhrs

It was supposed to be sunshine, rum cocktails, and absolutely no time travel.

Madison Carter was supposed to be celebrating her 23rd birthday with sunshine, rum cocktails, and zero responsibilities. When she visits an old sugar plantation turned historical museum, she finds herself drawn to a sealed-off part of the estate. An overgrown stone garden rumored to be haunted. When she touches a carved stone etched with strange symbols, she’s flung back to the late 17th century.
Brodie MacLeod has survived betrayal, captivity, and life aboard a ruthless French privateer. Hardened and haunted, the Highlander is now bound for a plantation ruled by a wealthy widow who collects rare and beautiful things, including men like him. When Maddie appears, barefoot, baffled, and very much not from around here, he suspects yet another trick of fate.

Mistaken for a governess, Maddie must play the part while searching for a way home, and a way to free Brodie. But the island is brimming with secrets. With danger closing in, Maddie and Brodie are forced into a fragile alliance that soon burns hotter than the Caribbean sun.
But when centuries lie between them, and freedom comes at a price, will love be enough to change their fate?

Through time, through turmoil, through every impossible moment, he was always hers.