Concert versions of Broadway musicals are usually a way to cut costs. With minimal costumes and no need for dancing, sets or lengthy rehearsal periods, the concert is a way to showcase great tunes and singers for a few nights. The concert version of "Sweeney Todd: The Demon Barber of Fleet Street" that airs tonight on Channel 26, however, feels anything but stingy, luxuriating in Stephen Sondheim's music and offering a wealth of first-rate performances.

It's a macabre story -- once a silent monster movie -- so PBS has served it up for Halloween (9 to 11 p.m.). The network evidently assumes that people will want to sit down after the trick-or-treaters have gone and watch a musical about a guy who slits people's throats while his sweetie cooks the corpses into meat pies But with George Hearn as Todd, Patti LuPone as his collaborator, Mrs. Lovett, and an equally superb supporting cast to give the extraordinary music its due, watching this show may not be a bad way to unwind.

Most of the leads, with director Lonny Price, staged this version in New York last year. They reprised it in San Francisco in July, and it is this production that was filmed. The San Francisco Symphony is seated on two levels, with the entire San Francisco Symphony Chorus seated in a row on the higher tier. (It will help if you have a television with a good sound system, as opposed to the static-filled tape producing station KQED sent out for previews.)

"Sweeney Todd," first produced on Broadway in 1979, has never been among my favorite Sondheim musicals. I prefer the interpersonal angst of "Company" or the showbiz homage of "Follies"; the cannibalistic ditties in "Sweeney" are truly disgusting to my tender digestion. It's wordy and overly clever, and many scenes, like the one in which Mrs. Lovett serves up her human meat pies while Todd is fussing over the pending arrival of his next victim, are so complex they become tedious.

But there are some wonderful songs, notably the lyrical "Johanna," "No Place Like London" and "Green Finch and Linnet Bird." Hearn, who did not originate the role on Broadway, has played it so often since then that he has made it his own. His rendition of "My Friends," in which Todd rediscovers his old barber tools after having been in prison for 15 years, is heart-rending. You almost forget he's a vicious sociopath.

Actually, in this retelling of the tale of an 18th-century English crook, Todd was given a backstory to sweeten him up. It seems he was originally named Benjamin Barker, and his beautiful wife was seduced by the nefarious Judge Turpin (played here magnificently by Timothy Nolen, another veteran of the title role). Framed by the judge, Barker was imprisoned in Australia, and his daughter, Johanna, was adopted by Turpin. Returning to London, Barker renames himself Sweeney Todd and sets out to get revenge, making an alliance with the jolly but unscrupulous Mrs. Lovett.

The show is known as a "dark" musical, which may be one reason it's often classified as an opera. Certainly the forces of darkness -- vengeance, betrayal, murder, theft -- dominate the faint rays of light represented by Johanna (Lisa Vroman) and the young sailor who loves her (Davis Gaines). Todd is a man whose worldview has been reduced to mistrust and hate, with a Brechtian philosophy that life is about "who gets eaten and who gets to eat." In this play, it's literally "man devouring man, my dear."

The concert format is actually well suited to this mordant work, highlighting the extreme philosophy without dwelling too graphically on the throat-slitting, body-grinding, meat-pie-eating aspects. Director Price (Sondheim aficionados will recall that he had one of the leads in the original cast of "Merrily We Roll Along") has organized the proceedings with elegance and style.

LuPone's wonderfully theatrical talent is perfect for the over-the-top Mrs. Lovett, and she's a fine counterpoint to Hearn. Neil Patrick Harris (always saddled with his past as "Doogie Howser, M.D.") is nicely slimy as her assistant, Tobias Ragg, and Gaines is bright and lyrical as the ingenuous and aptly named Anthony Hope, a man alone.

Real cutups: George Hearn and Patti LuPone star in the concert performance of Stephen Sondheim's "Sweeney Todd" that airs tonight on PBS.