It's tough to squeeze fresh life out of a legend as overtilled as Camelot, but Merlin, a 13-part summer series on NBC, debuting tonight, finds a workable approach: Dial the traditional tale back a few decades and twist the premise.

Forget the Round Table; say hello to the Kiddie Table.

This BBC import, exceedingly handsome but poky, takes King Arthur and his wizard Merlin back to their days as shavers.

Trivia note: NBC broadcast a TV movie with the same title and covering the same hallowed ground back in 1998. What a cast that film had: Sam Neill, Helena Bonham Carter, John Gielgud, James Earl Jones, Miranda Richardson, and many more.

This new series is built around a pair of young newcomers.

Merlin (Colin Morgan) is a wide-eyed youth, newly arrived at the castle. He enters like a student traipsing across Europe on summer break, with his bedroll on his back. Val-der-i, Val-der-a.

Arthur (Bradley James) is the arrogant prince. His father, Uther Pendragon, sits on the throne. (And sounds like a great '70s soul singer - a hybrid of Luther Vandross and Teddy Pendergrass.)

Pendragon, the ruler of Camelot (Anthony Head, best known as Giles on TV's Buffy the Vampire Slayer) is a tyrant who has stamped out sorcery in the kingdom. Use of enchantments is punishable by death.

That draconian edict poses a significant problem for Merlin, because the new kid at court comes equipped with abundant magical abilities that he must keep tightly under wraps. He's like Samantha Stephens at one of Darrin's office parties.

The two lads, Merlin and Arthur, become instant antagonists. It takes the great dragon (voiced by John Hurt), held captive in the vaulted catacombs beneath the castle, to explain how their fates are intertwined.

Merlin is sumptuous in a way American TV series rarely are - richly atmospheric, with lush production values, and laced with good special effects.

OK, its occasional stabs at humor are lame, but the 6th century, by all accounts, wasn't exactly a barrel of laughs.

When it comes to the Arthurian lore, it's always tough to separate history from legend. But it's obvious some liberties have been taken with castle life.

The king's physician, Gaius (Richard Wilson), for instance, pops on a pair of reading glasses. Seven centuries too early for that amenity. And one knight in a battle tournament employs acrobatic kung-fu skills. Why you would want to sweep-kick someone wearing armor is a mystery to me.

The two young leads, Morgan and James, lend this series most of its appeal. But the cast is uniformly good.

Can someone please explain why British actors are able to bring so much more conviction and gravitas to these costume epics? American actors only seem to grow sillier the further they are plunged into the mists of time.

Despite the good performances and the detailed medieval window dressing, Merlin still has the impact of a warm glass of milk. You are getting sleepy . . . sleepy.

The series is heavy on ambience, light on forward momentum. The syndicated series Legend of the Seeker has a similar sword-and-sorcery setting. It may look almost laughably chintzy next to Merlin. But at least Seeker keeps its narrative top spinning.

Merlin did big numbers in Britain when it ran there a couple of years ago. Its patient, stately approach may earn it a frostier reception on this side of the pond.

Contact staff writer David Hiltbrand at 215-854-4552 or dhiltbrand@phillynews.com. Read his recent work at http://go.philly.com/daveondemand.