One of Bujold's forays into fantasy, this couldn't be more unlike the Barrayar series, which is not to say that it's bad, just very different.
We first met Ista, the dowager Royina of Chalion in 'The Curse of Chalion', where she might have been mad, or she might just have been worried to death for the fate of her children.
With the Curse lifted, Ista's frenzied worrying is relieved, but she is still in Valenda and her family are still under the impression that she's crazy - she isn't, she's just bored.
After meeting and talking with the 'Wife of Bath's' Chalion double, Ista decides to go on a pilgrimage, with just a young divine of the Bastard's order and a messenger girl. Just a jaunt round a few holy places to blow the cobwebs out of her brain. (To quote one of Bujold's other books 'Met the Chance brothers lately? No and Fat'.).
Although this can be read as a stand alone story, reading the 'Curse of Chalion' first is a good introduction to the religion and characters in both books. Either, or both, are excellent, well plotted, well written, with plenty of excitement as well as some interesting philosopical musings. Highly recommemded.