Grail of the Summer Stars is the third in Freda Warrington's Aetherial Tales series, following Elfland and Midsummer Night. Each novel can stand alone, though they have some overlapping plotlines and characters, such that each novel will be more meaningful and resonant if you've read the others. Grail of the Summer Stars has more overlapping elements than either of the two previous books and is connected more strongly to each of them than they are to each other.
Warrington introduces us to Stevie Silverwood, a metalworking artist and museum curator who has always been a little odd, seeing things no one else could see -- and whose past before age 15 is a mystery even to herself. Her quiet life is disrupted when her old college sweetheart, Daniel, sends her a triptych of fantastic paintings along with a cryptic note, and goes missing. Her path soon crosses with that of Mistangamesh, an Aetherial man whom we met in Midsummer Night. He is hunting for his brother, Rufus, intending to kill him. Their subsequent search for Daniel and for the paintings' meaning draws them into a millennia-old mystery involving Mist's family and a megalomaniacal plot that could destroy both the Earth and the Spiral.
Like the previous Aetherial Tales novels, Grail of the Summer Stars features beautiful prose and themes of finding and being true to oneself, of love, of troubled family relationships, of art as a manifestation of magic and as a form of magic in itself. Warrington expands on another corner of her Aetherial world here, and it's hard to imagine that there's any end to her treasure trove of ideas. The pace is faster this time out; while there is an epic, sweeping past behind this novel's plot, there is a race-against-time feel to the modern-day action, and the book is the shortest of the series (so far).
Warrington's plotting is tight and nothing is wasted. One is continually surprised, while reading Grail of the Summer Stars, as what seemed like throwaway details come back to make total sense and to tie in with the central plot. This is true both of elements introduced in this novel and of threads from the previous two; as mentioned above, material from the earlier books is woven into this one, often in surprising ways.
I highly recommend the entire series to anyone looking for an inventive fantasy world that intersects with our own, for intricate plotting, and for characters you will feel for and feel like you know personally. Warrington could theoretically stop here and have a satisfying trilogy, but I hope she has many more Aetherial Tales to tell. Her universe is certainly rich enough to contain them.