Audiences settling in for a three-hankie sob session when the Julia Roberts-Susan Sarandon weeper "Stepmom" hits theaters on Friday may be surprised to find their sniffling time cut short by song-and-dance shtick.

Shortly after Sarandon announces to her young children that she has cancer, all hell breaks loose as her older daughter (played by Jenna Malone) begins spitting out venomous comments about her miserable life as only an adolescent can. Serious illness, lost innocence, family strife -- what better time for a song? Minutes later Sarandon and her offspring are prancing through the house in their jammies, singing "Ain't No Mountain High Enough" into hairbrushes, and boogying to beat the band. In another scene Julia Roberts, also realizing the quickest way to a kid's heart is through the use of old Motown tunes, manages to lull the cantankerous Malone into submission by crooning along with the radio.

Scratching your head? Director Chris Columbus isn't. An old pro at the lip-synch game, Columbus relied on impromptu karaoke to pump up the action in "Adventures in Babysitting" and "Home Alone." "It's always easy to work your way out of a difficult moment with a nice little song or dance," explains EW senior writer David Hochman.

Since the "The Big Chill," it seems that hardly a movie escapes the studio gates without some kind of fancy footwork and vocal miming being worked into the plot. "Reality Bites," "Beatlejuice," "In and Out," "The Cable Guy," "Mermaids," "Reservoir Dogs," and according to Hochman, "just about every John Travolta movie" are just a few on the list. Who said musicals were dead?

But with such numbers becoming more routine, they're less likely to pack a punch. In the case of "Stepmom," hoofing it around the living room with the stereo on doesn't distract from the fact there's a gaping hole in the plot and that character development is shoddy and uneven. "I think it was jarring that you would go from this heavy emotional moment to this little Motown ditty," says Hochman. But scratching the disco fever may not be the solution. "Considering that a lot of the other elements were weak in 'Stepmom,'" says Hochman, "I actually think they needed a lot MORE singing and dancing."