"Power from the green witch, lost beneath the sea..."
- from a prophecy outlining the quests within this series
Although GREENWITCH is the third of the five books within this series, it is more nearly a sequel to the first book than the second because in a way it is a completion of the individual quest begun in OVER SEA, UNDER STONE. GREENWITCH could be read without having read the second book, although having done so will give the reader a truer perspective on one of the characters introduced in that book.
Like each of the other books in the series, GREENWITCH manages to inject new complications into the six main characters' relationships with one another. At this point, five of the six have been introduced (the three Drews and Merriman Lyon in the first book, Will Stanton in the second), but the Drews have never met Will, and as his presence is not explained to them, they naturally resent him a great deal at first as an unwelcome intruder (unaware that he knows more about what's going on than they do, despite how matters appear on the surface). The presence of the Drews makes the story particularly enjoyable, as they provide a genuine Everyman point of view amid all the mysteries of this series of quests and battles against the Dark, in contrast to the equally interesting but different perspective of the more knowledgeable and powerful characters.
In a way, the story picks up exactly where the first book ended, but in a very different mood - the Drews are standing in the same place in the British Museum and looking at the same thing, but in dejection rather than triumph. For the Trewissick grail discovered in the first book has been stolen by a mysterious agent of the Dark, who hopes to complete the quest left unfinished the previous summer, an agent about whom even Merriman and Will know very little.
As in each book in the series, this quest takes place at one of the great festivals of the Celtic year, here the spring festival still observed in Trewissick by the making of the Greenwitch, a great leafy image made by the village women in a single night and ceremonially thrown into the sea upon the fishermen's return at dawn. Unknown to the villagers, the Greenwitch belongs to the Wild Magic, a force not allied to either the Light or the Dark in their long struggle, and of which we have seen little in the series up to this point.
And the Greenwitch - which awakens each year after being given to the sea, and has a brief, independent, and immensely lonely existence before being swept out to the deeps - has its own agenda, which like the Wild Magic is independent of the needs and desires of either Light or Dark, and like it must be persuaded rather than compelled to cooperate. The Greenwitch's character is particularly compelling - it depends on humans for its very existence, but its few days of independent life each year are so bitterly lonely that it easily feels resentment against everything else in the world, for allowing it to be made and then cast out uncomforted.
Most unfortunately for both sides, the lost portion of the object of power known as the Trewissick grail - lost even when the grail itself was first found - has entered the sea, making it subject to a power indifferent to their war. Worse, it lies dangerously near the Greenwitch's temporary resting place, in the control of a creature whose inherent wildness coupled with its bitter feelings makes it very dangerous to approach.
This book is well worth reading, and doesn't suffer from being the middle portion of a longer story. While it is best read after reading the story to date, it is in itself an important quest, and achieves a great thing (though the greatest achievement in the story may not be what the reader was expecting). Furthermore, in addition to showing us the Wild Magic as yet another side and another perspective to the great magical forces that operate mostly outside human awareness, this book adds a twist in the form of the Dark's mysterious agent, whose character is very distinct from those of the great lords who tend to be the Dark's representatives in other books, and who thus gives us a new perspective on the Light's ancient enemy.
In addition to the book itself, I highly recommend the unabridged audio edition read by Alex Jennings. Hearing the voices of the Cornish characters in particular is a treat.