• Being Human, 9-10 p.m. Saturday, BBC America

Come and knock on our door . . . and you might get eaten. Mitchell's nice enough, except he keeps sinking his fangs into all his friends. George single-handedly keeps IKEA afloat by wrecking all the furniture when he turns into a wolf every full moon. And Annie's jittery insecurities about her looks have certainly not been calmed by her death. Toto, something tells me we're not in Three's Company territory anymore.

Indeed not. Being Human, a surprise hit earlier this year in Great Britain that's now being exported to the colonies, is not the silly sitcom its premise -- a vampire, a werewolf and a ghost rooming together -- suggests. Neither is it a Gothic slice-and-dice of politics and culture like HBO's True Blood.

What it is is darkly funny, deeply affecting and utterly cockeyed, a work that celebrates life by dwelling on death, love by abiding loneliness. It's a tale of cold, dead noses pressed up against the window pane of humanity. ``Here we are, overlooked and forgotten, unnatural and supernatural, watching the dance from the sidelines,'' muses Annie. ``Refugees, the flotsam and jetsam of death.''

Not that Being Human doesn't have purely comic moments as it explores the domestic complications of monsters trying to blend in among human neighbors. George, Mitchell and Annie (played by the relatively unknown British TV actors Russell Tovey, Aidan Turner and Lenora Crichlow) are trying to suppress the darker manifestations of their supernatural selves at the same time they struggle with the ordinary romantic and workplace dramas of 20-somethings.

George's fractured explanations to landlords as to why there's not a stick of furniture left in the house after the full moon (the roommates were gripped with a sudden, frenzied anti-materialism) are as unlikely as his excuses to women when he breaks off flirtatious conversations to go howl at the moon. Annie's pratfalls as she obsessively stalks the fiance she left behind are no less hilarious for their predictability.

But for all the laughs, Being Human never loses sight of the menace of its characters. When Mitchell suffers a relapse while attempting to go off blood cold-turkey, with disastrous results for a co-worker at the hospital where they work as orderlies, George is horrified: ``For Christ's sake, we knew her!'' So is Mitchell himself when he encounters the woman later, now sprouting fangs and urging him to join a vampire underground plan to revolt against humanity: ``Let's just take their world and tear their children to shreds!''

Her jealous rage frames the central question of Being Human: whether life is wasted on the living. ``They had their chance,'' another vampire tells Mitchell. ``We left them to tend this paradise, this Eden. And look what they did.''

But the point is more often in poignance than in anger. When Annie learns that her still-breathing fiance has a new girlfriend, George tries to comfort her: ``You're much prettier and much nicer.'' To which she replies, sadly and irrefutably: ``And much deader.''