Scottish Highlands. Time travel. Immortality. Sounded like just the thing for a long flight home for the holidays, right?
Nope. Skip this one, folks.
There were several problems with logic and continuity - a character knows something in one scene that they have no way of knowing, then have forgotten they knew it in the next chapter; this gets to be disruptive for the attentive reader.
Major plot points were skipped completely (the room with the potions and the star maps, for example. Why make such a big deal out of this if they were never to be seen again?).
What was the point, also, of Marcail and O'Donnell? Neither character was particularly well-drawn or even all that likable, so it really didn't matter to the reader whether or not they ever decided to join.
Many of the scenes were short - 3 or 4 paragraphs or no more than a page - but they would jump characters and even jump 2 or 3 days from the previous scene. Unfortunately, in jumping over the days, the author missed telling big chunks of story. Considering that the time travel portion only covered 28 days to begin with, she didn't have the luxury of skipping days.
Pass this one up. If you want immortality and the Scottish Highlands, watch "Highlander" (the first movie). If you want time travel and the Scottish Highlands, read Diana Gabaldon's "Outlander."
I definitely will not read more by this author.