Once she arrived in London this was fine but in Ireland it was plain to see that the author had no idea what Ireland of the period was like, she did read Hardiman's History of the Town and Country of Ireland but it appears failed to properly look at topographical maps of the area. And I was so looking forward to reading a book that included Galway. Sigh.
Look, I'm from Galway, in the first Elizabethan era it was a walled city, within these walls were most of the gentry of the area, excepting a few who had a lot of retainers and soldiers. I know that the plot required her to be outside the walls but it's not good.
No, most castles in Ireland don't have moats, outside of, mostly, the Pale. And an envoy for the queen would have been nearer Dublin, probably somewhere along the East Coast. The west was not an easy place for the English, up to and including Oliver Cromwell. At this time Brehon Law was legit in the area and it complicated a lot of English ruler's lives. But it all felt very English.
A viper falling from the thatch.... a viper? FFS. Even now, with a few escapologist snakes, the snakes in Ireland are in Zoos or are pets.
Going from Galway to London was handwaved away but was implied that there was a long time on boat or boats. That would have been worse than unpleasant, the logistics of it are mindbending. The only parts mentioned are across the Irish Sea (how did she get from the Atlantic to there) and then up the river to London, how were the parts from Irish Sea to river-to-london done? Honestly it sounds like a trip to do in any other season than winter.
Signal fires from Dublin... these days it's a 2.5 mile drive. Signal fires may originate in Dublin but they come from elsewhere.
Cliffs visible from the castle they had... cliffs? Where are we?
We will not discuss how Dunboyton contains too many name sources for the era. Galway is a west of Ireland county, so Dún is fine, there are many Dún's around the area, Boy could be some sort of mishearing, so i'll let that one slide but the Ton is usually from earlier variations of Town, and is of Norman origin, and there are no real towns in the area, a village yes, but no town so the name place actually makes no sense. Beau Maris or Belleview or Queens Castle would have been more fitting based on the "cliffs"

Lady Alys Drury rescues a Spanish Armada sailor who calls himself Juan (oh and she's half-spanish and that's strange here, which forced me to blink lots in Galwegian, even before the Spanish Armada, there were Spanish Merchants in Galway, see Spanish Arch) who absconds after he heals and then she meets him again when she goes to the royal court.

It's not terrible and if you don't know details about Ireland and particularly Galway it would probably work but I couldn't just let it slide, dear Authors, Google Maps is your friend. For an Irish Woman of the Period please see the neighbour Grainne Mhaol.

I may have ranted a little about this book in my twitter feed. ( )