Her first film of note was "I've Heard the Mermaids Singing" (1988), which won the Prix de la Jeunesse at the 1987 Cannes Film Festival. The redheaded, saucer-eyed McCarthy played a 31-year old photographer who can't organize her life, but through working for a lesbian art gallery owner comes to terms with herself as an artist. By 1990, she was dividing her time between Canada and the US. Her first American film was the independent and little-seen Dermot Mulroney vehicle "Bright Angel" (shot in 1989; released theatrically in 1991). Other prominent roles include the reporter who lends Bruce Willis a hand in "Die Hard 2" (1990) and the pseudo-worldly waitress friend of Melanie Griffith who is no stranger to sexual encounters in "Paradise" (1991). At the opposite end of the spectrum was her quiet member of Liza Minnelli's tap-dancing class who, as it turned out, was battered by her husband in "Stepping Out" (also 1991) and the mother of a girl who uses black magic when she finds out her father is cheating in "The Lotus Eater" (1993). She and Christopher MacDonald play battling spouses held captive by their children in "House Arrest" (1996).
A veteran of Canadian TV dramas, McCarthy began appearing in American-seen TV programs prior to her work in US features. She was a wife whose husband takes up smoking in "Trying Times" (PBS, 1989). The following year, she appeared in an unsold pilot for a series version of "Steel Magnolias", as Annelle (Daryl Hannah's role in the feature). McCarthy was in support of Sissy Spacek in "A Private Matter" (HBO, 1992) and played Jill Lansing, Lyle Menendez's attorney, in the 1994 CBS miniseries "Menendez: A Killing in Beverly Hills". She also co-starred in the 1995 NBC miniseries "A Woman of Independent Means", provided the voice of Annie in the animated series version of "Free Willy" (1994-96) and had a recurring role as the love interest to medical examiner Carter Pike (Kelly Connell) on the CBS drama series "Picket Fences" (1995-96).