West of the Moon (WotM) is the one-volume version of Katherine's trilogy (Troll Fell, Troll Mill, and Troll Blood) - none of which I have read in their separate incarnations. WotM combines these tales flawlessly, in a coming-of-age tale where the supernatural aspects of trolls and house-spirits are as readily accepted as the more usual fishing and milling exploits that one might expect from a Viking Age settlement.
The trilogy begins with a funeral, Peer Ulfsson's father is sent on "the long journey to the land of the dead" on the very first page. Immediately, the reader sits on Peer's shoulder and watches with increasing trepidation as he finds himself in the hands of his hitherto unheard of half-uncles, Baldur and Grim. I was hooked from that fiery beginning, thrilled when the free-spirited Hilde swept her way into his life, and grinned like a loon with Hilde and Peer's quick thinking against the trolls of Troll Fell (who might be as common as pigeons are today, but seem to be both infinitely more troublesome and slightly less intelligent in Katherine's Scandinavian world!).
The second installment opens as years have passed, and characters who were once heroically worshipped are now honoured friends ... although that friendship is tested before this part is finished! Peer, now a somewhat gawky teenager, has to contend with the terrifyingly coherent Granny Greenteeth (again!) the lakewife of the millpond, the trolls (again, and with a twist!), and the realities of growing up and finding out things aren't quite what he expected.
Finally, Peer ventures across the sea - a voyage that promises little but uncertainty from the outset. The group of voyagers range from now-familiar Troll Fell folk, `revered` warriors, seasoned seamen, and more than one with supernatural blood! If the first book is rooted in the earth (underground trolls, earth spirits, and literal changes of land) and the second flows with water (Granny Greenteeth, seal-lore, and fishermen galore!), then this third book combines those two elements expertly as we are carried with Peer to Vinland - the land "east of the sun, west of the moon".
Katherine Langrish has created a world where today's myth and reality walk side by side (although, the mythic parts might be lurking in the shadows next to you!) and you barely realise that this is new and different. If these books had been written a decade earlier, I'd have chewed my way through them then and probably spent hours trying to draw scenes from them (as I might have done with a certain Tamora Pierce's characters back in the day!) and yet more time imagining the place I'd have held in this well-crafted world. As it is, I might have spent some time doing the latter, and I look forward to my son growing up enough to appreciate these, as I know that he will. The myths intertwine together, magic and realism holding hands, in a way that I love.
Recommendation: If you're intrigued by Vikings, love myths, and want to step into a world where the supernatural creatures are a day to day occurrence (and often an unwanted one!) then you might be intrigued by this trilogy. Combine this with a coming-of-age tale that will stay with you, and West of the Moon is a book to read, enjoy, and read again!