Mary Stewart's Merlin trilogy and post-Merlin climax, The Wicked Day, have long stood out among the best of the Arthurian novels on the market. Unfortunately, filmmakers rarely choose the good ones as sources for their movies -- but there is a little-known adaptation of Stewart's first novel, The Crystal Cave, on the market.

The BBC's Merlin of the Crystal Cave was originally released as a six-episode mini-series in 1991. Later collected on video, the film follows closely the events as described by Stewart, although some incidents and characters are combined or omitted by Steve Bescoby's screenplay.

You'll not find big-budget special effects here; for that, check out 1998's NBC mini-series Merlin, starring Sam Neill. However, Crystal Cave provides a more satisfying story, with a treatment of the characters who adhere more closely to legend than the fantasy-burdened '98 version.

The acting doesn't always shine, either. Action is stilted at times, and the film certainly could have used a better fight choreographer to iron out some awkward swordplay. Sometimes, you can't help but wonder if one more take wouldn't have helped. But this is a case where the story is strong enough to stand alone; while the production quality isn't top-drawer, it's sufficiently good not to detract too much from the plot.

And, while Crystal Cave doesn't boast Oscar-worthy performances, the majority of actors are strong and sure in their roles.

George Winter makes a good Merlin in his early adulthood. He is confident and assured without being cocky. His younger selves don't fair as well; Thomas Lambert and Jody David are competent, presenting a calm and inquisitive child, but they're less solid when extremes of emotion are called for. The voice-over in Merlin's youth is exceptionally annoying; the voice doesn't match the motion, and I feel at times when he's speaking like I'm watching low-budget anime.

Strong performances include Robert Powell as Ambrosius, Roger Alborough as Uther, Mark Williams as the Saxon slave Cerdic, Benedick Blythe as Merlin's ambitious uncle Camlach and Don Henderson as Merlin's aged teacher Galapas.

Particularly good is Kim Thomson as the lovely and serene Ninianne, Merlin's mother, who carefully conceals his father's identity from her royal family. Considering how much British cinema I watch, I'm surprised not to have seen more from Thomson -- although she did pop up for a brief but crucial scene in the hilarious Jeff Goldblum vehicle, The Tall Guy.

Trevor Peacock is also good as the servant Ralf, although the movie's setup -- which requires Ralf to ask Merlin to describe his younger days, despite Ralf's presence at many of the key events described -- is awkward.

Watching Crystal Cave, you never lose the sense that you're watching a made-for-TV movie. It doesn't have the big-screen feel despite the grandness of events being depicted. This is where viewers must choose their priorities: while other Arthurian movies can boast better effects and better acting (in some cases, anyway), Crystal Cave has most of them beat when it comes to the story itself.

Beginning with young Arthur's king-making, the movie rolls back into a series of flashbacks, starting with Merlin as a young bastard child in a rough Welsh court. He learns to ride and fight from the slave Cerdic and learns science and magic from the hermit Galapas, all the while dodging half-hearted assassination attempts by his uncle Camlach, who fears an adult Merlin's claim to the throne. When intrigue builds to the boiling point, Merlin flees his home, only to be captured by spies from Ambrosius, who waits in Brittany with his brother Uther for the right moment to invade Britain.

Merlin grows into a vital strategist, despite Uther's continued distrust. Soon he returns to Britain to help direct events which will put Ambrosius on the High King's throne.

The biggest problem of the film is that it ends where it does, and that the BBC never followed through with adapting the remaining volumes. (It does end satisfyingly, though -- the story doesn't leave you hanging the way Ralph Bakshi's animated but uncompleted The Lord of the Rings feature does.) Still, you walk away from Crystal Cave wanting more, to see what happens next with Merlin, Uther and, eventually, Arthur himself.

Still, Arthur shines in numerous movies. This one focuses on Merlin's early years, and it does an excellent job of bringing the magic and wonder of those years to life while establishing events leading up to the golden age of Camelot. That's reason enough for genre enthusiasts to give The Crystal Cave a look.