Thank you to the few people who recommended this trilogy. I've 90% finished this sequel now (only 90 because I fell asleep before I could finish it the rest of the way, and also because I was in a pixel art vortex yesterday after my soul inscrutably exhorted me to make a pixel art icon of my favorite art nouveau radio, the Australian AWA Fisk Radiolette Fret & Foot in Lime bakelite. ~Fun fact: bakelite is called bakeliiti in Finnish. - )
Anyway, I can only enthusiastically pass on the recommendation. The setup of this book involves three young women who are determined to find out what happened to the titular Riddle-Master and evidently killed him before the book began:
And because they're young women everyone wants them to stay as safe at home as possible, so they run away together and steal a ship to do it. In fact, they run away in the course of their quest multiple times, including from each other, but it doesn't really get old.
On the way, they're encountering a much older mystery about the foundation of the magic in their high fantasy world - the same one the Riddle-Master was tangled in: a mysterious ancient race who inhabited their land before them and what happened to them; the meaning of an ancient prophecy; the rise and sudden disappearance a few centuries in the past of the college of wizards; the mysterious absence of the magical-religious high ruler who presides over all the kings in their land; a mysterious vendetta on the part of some shapeshifters, and the nature of shapeshifters themselves (presumably).
I love mysteries about the old foundation of magic in a place, and I love vanished magical ancient races, and I love characters figuring out their magic powers for themselves, so this is all great. These elements were actually in the first book too, and the writing style is very similar, but I was less impressed by the internal hero's journey of the narrator there (the titular Riddle-Master again) than by the internal hero's journey of Ræderle in this one.
ETA. Okay, and also... this book is vintage, so when I googled it I turned up no less than SIX hilarious vintage covers.

Despite the fact that the vast majority of the fantasy names are clearly Celtic and the climates and locales described are also pretty British, we have here a 70s kaftan/kimono type gown (1) and a kind of... Faerie Queen headdress with a short-sleeved silk?? jacket?? with trailing 1930s scarves of course (3), just typical pre-industrialized, feudal farming society traveling gear for sailing and horseback riding and foresting I guess! Then we have the extremely bold choice to go for Ancient Greece complete with karyatids from the German cover there, and even bolder, a disco dancing queen emerging from the ocean in (4), and I honestly suspect this cover was painted for a different book entirely because the only thing this seems like it could be is, I guess, a shapeshifter assassin emerging from the ocean offscreen before coming to assassinate people??. Then there's a very nice decolletage-focused blue ballgown that looks a bit Regency reminiscent, but not really, in (5) and is rendered slightly more practical than 1. and 3. only because it is worn with a frock coat with gold padded trim that at least covers her arms even if it doesn't fasten anywhere; and finally, (2), which seems plausible enough that I won't argue with it really, although I will say that her hair should be bound up, like women's and long hair almost always should in these sorts of fantasies and almost never is. But possibly it's been up and she has just unbraided it in order to put it back up again later.
Anyway, I can only enthusiastically pass on the recommendation. The setup of this book involves three young women who are determined to find out what happened to the titular Riddle-Master and evidently killed him before the book began:
- Ræderle, 3rd child of the King of An (but all these kingdoms are like little counties or duchies size-wise, that you can cross on horseback in a day or so), his childhood friend and betrothed, a minor magic-user who inherited the true sight of her distant shapeshifter ancestor;
- Lyra, eldest daughter and heir to the Queen of Herun and captain of the Queen's bodyguard, whose honor was wounded because someone got past her to attack him when he was her guest;
- Tristan, the titular Riddle-Master's 13-year-old sister and youngest sibling, third in line to the throne of Hed.
And because they're young women everyone wants them to stay as safe at home as possible, so they run away together and steal a ship to do it. In fact, they run away in the course of their quest multiple times, including from each other, but it doesn't really get old.
On the way, they're encountering a much older mystery about the foundation of the magic in their high fantasy world - the same one the Riddle-Master was tangled in: a mysterious ancient race who inhabited their land before them and what happened to them; the meaning of an ancient prophecy; the rise and sudden disappearance a few centuries in the past of the college of wizards; the mysterious absence of the magical-religious high ruler who presides over all the kings in their land; a mysterious vendetta on the part of some shapeshifters, and the nature of shapeshifters themselves (presumably).
I love mysteries about the old foundation of magic in a place, and I love vanished magical ancient races, and I love characters figuring out their magic powers for themselves, so this is all great. These elements were actually in the first book too, and the writing style is very similar, but I was less impressed by the internal hero's journey of the narrator there (the titular Riddle-Master again) than by the internal hero's journey of Ræderle in this one.
ETA. Okay, and also... this book is vintage, so when I googled it I turned up no less than SIX hilarious vintage covers.

Despite the fact that the vast majority of the fantasy names are clearly Celtic and the climates and locales described are also pretty British, we have here a 70s kaftan/kimono type gown (1) and a kind of... Faerie Queen headdress with a short-sleeved silk?? jacket?? with trailing 1930s scarves of course (3), just typical pre-industrialized, feudal farming society traveling gear for sailing and horseback riding and foresting I guess! Then we have the extremely bold choice to go for Ancient Greece complete with karyatids from the German cover there, and even bolder, a disco dancing queen emerging from the ocean in (4), and I honestly suspect this cover was painted for a different book entirely because the only thing this seems like it could be is, I guess, a shapeshifter assassin emerging from the ocean offscreen before coming to assassinate people??. Then there's a very nice decolletage-focused blue ballgown that looks a bit Regency reminiscent, but not really, in (5) and is rendered slightly more practical than 1. and 3. only because it is worn with a frock coat with gold padded trim that at least covers her arms even if it doesn't fasten anywhere; and finally, (2), which seems plausible enough that I won't argue with it really, although I will say that her hair should be bound up, like women's and long hair almost always should in these sorts of fantasies and almost never is. But possibly it's been up and she has just unbraided it in order to put it back up again later.