What would you do if you went on a school trip, got lost in the mist and emerged 1,200 years in the past with invincible fighting strength and magical powers? When sporty, popular Dan and fat, weird Ursula got lost together in N.M. Browne's Warriors of Alavna, it was the start of an electrifying journey in which they wound up impersonating King Arthur to bring justice to Britain in its Dark Ages.

One of the very best magical adventures of the past 30 years, Browne's Warriors trilogy reaches its conclusion this week. If you missed it and have a child who loves time travel, swords and serious violence then don't hesitate to get the first two as well as Warriors of Ethandun. The second, Warriors of Camlann, had Dan bringing the mortally wounded Ursula back to our own time for modern medicine to save her. Grown and changed they have, inevitably, fallen in love - but back in our world, everything is different. Gorgeous Ursula is now popular, but Dan is shunned as a suspected psychopath. Then Ursula almost kills the school bully and both are in trouble. The magician Taleisin has given them a means to return through the “seething yellow mist” of the Veil. Just in time, for they are needed by the greatest of all kings - Alfred.

Weary, discouraged and beset by Vikings, Alfred is hiding out in the marshes and burning his hostess's cakes when Dan stumbles upon him. Ursula, however, is trapped elsewhere by the magical power that surges through her, and lies dreaming, worshipped as the goddess Freya by the enemy. How can Dan reinvigorate King Alfred's campaign? How can Ursula be woken from working magic against the Anglo- Saxons, and apparently demanding human sacrifice?

Fans of the series disappointed when Dan turned pacifist in the second novel will be delighted to learn that it's not long before his sword, Bright Killer, is slicing human guts again, with the loyal hound Braveheart snarling by his side. By making her hero a Berserker, Browne conveys both the horror of violence and its dream-like delight. (Interestingly, all the best writers of gory battle scenes now seem to be female, from Susan Price's The Sterkarm Handshake to Lian Hearn's Tales of the Otori.) The quality of prose describing Ursula's ecstatic near-madness from magic is just as good. Her consciousness flits from her body into fire, earth, animals or birds; filled with power over the natural but without compassion, she is in a different kind of peril unless Dan can save her, and drive out the Danes.

Browne has always been best at this kind of writing - Hunted, one of her earlier novels, was about a dying teenage girl's spirit entering the body of a fox. She can take it too far into a kind of post-hippy mysticism (as in The Story of Stone) but she is part of a grand Celtic storytelling tradition in British children's literature that began with Kipling's Puck of Pook's Hill, continued with T.H.White's The Sword in the Stone and blossomed in Tolkien and Alan Garner. That deep feeling for our landscape is something that needs reawakening. Wrapped up in an adventure that the less contemplative will find irresistible, the conclusion to the Warriors trilogy is both thrilling and superbly imagined.

Warriors of Ethandun by N.M. Browne
Bloomsbury £6.99 pp372 Buy the book

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