A bloody musical about a homicidal barber and his human-pie-making partner doesn't exactly sound like standard Christmas viewing, but that doesn't bother director Tim Burton (Charlie and the Chocolate Factory). ''Red is a color at Christmas,'' he jokes. Actually, the director thinks that his adaptation of Stephen Sondheim's classic musical might make for a better Valentine's Day option. ''For me, it sort of sums up relationships,'' says the director. ''Although people might be horrified by that.''

The movie's unrequited-love story also appealed to Helena Bonham Carter, who, fortunately for Burton, is his real-life paramour. ''There's still such a humanity to it, and that's what Tim always brings,'' says the actress, who plays the bizarro baker. Still, Bonham Carter admits that working with her significant other ''has its stresses.'' Luckily, her costar is more or less unflappable. '' (Johnny Depp) was really diplomatic. Whenever Tim and I started arguing, he would just look away.'' Burton considers this film one of his most challenging productions yet, which means a lot coming from the director of Beetlejuice, Batman, and Edward Scissorhands. ''To do an R-rated musical with 70 percent singing was kinda like, 'Well, I haven't done that one before.' It's exciting to keep surprising yourself and see what happens.''

Depp, like most of the cast (including Sacha Baron Cohen as a rival barber in his first post-Borat role), signed on having little or no professional singing experience. ''He was game for it,'' Burton says of Depp. ''When I first heard him, I was amazed.''

The vocals were more taxing on Bonham Carter, who felt like she was training for ''a sport.'' She also logged hours in the kitchen in an effort to learn the fine art of baking. ''I had to do accelerated lessons at pie making,'' she says. ''Not only that, but then you had to do it to syncopated Sondheim rhythm and sing at the same time. I had to become very coordinated.'' More enjoyable was her transformation into ghostly Mrs. Lovett. ''The look is fantastic,'' she says. ''I'd wear this makeup anyway. But it might start a whole craze.'' Let's just hope her recipes don't catch on.