Plunkett graduated from the
University of New Hampshire, and was a founding member of Portland Stage repertory company in Maine. She appeared on Broadway as
Bernadette Peters's replacement in the role of Dot in
Sunday in the Park with George in 1985. In 1987, she won the
Tony Award for Best Leading Actress in a Musical for her performance as Sally Smith in
Me and My Girl. She was part of the
Tony Randall's
National Actors Theatre company, and performed in their production of
Saint Joan by George Bernard Shaw in 1993 on Broadway. She performed in the National Actors Theatre productions of
A Little Hotel on the Side by
Georges Feydeau and
Maurice Desvallières on Broadway in 1992, and in
The Seagull by Anton Chekov in 1992. Plunkett appeared in the television movies
The Littlest Victims and
Breaking the Silence, and in feature films including
Claire Dolan and
The Company Men. She guest-starred on episodes of
Matlock,
L.A. Law,
Murder She Wrote,
Miami Vice,
Star Trek: The Next Generation, and
Law & Order. She and her husband, actor
Jay O. Sanders, appeared together in all four of
Richard Nelson's
The Apple Family Plays:
That Hopey Changey Thing, Sweet and Sad, Sorry, and
Regular Singing. They premiered at the
Off-Broadway The Public Theater in 2010, 2011, 2012, and 2013 respectively. Plunkett was nominated for the 2013
Drama Desk Award for Outstanding Featured Actress in a Play for her performance as Barbara Apple in
Sorry.
Sweet and Sad won the 2012 Drama Desk Award for Outstanding Ensemble Performance and the 2012 Obie Award for Ensemble Performance.
The Apple Family Plays played in repertory at The Public Theater from October 22, 2013, to December 15, 2013. Plunkett and Sanders appeared in all three productions of Richard Nelson's second play cycle,
The Gabriels: Election Year in the Life of One Family, which premiered at The Public Theater. Plunkett portrayed Mary Gabriel and Sanders portrayed George Gabriel, her brother-in-law. The first play,
Hungry, premiered in March 2016. The second play,
What Did You Expect?, ran from September 10, 2016, to October 9, 2016. The third and final play,
Women of a Certain Age, opened on election night, November 8, 2016, and ran through December 4, 2016. In 2024, she won an
Obie Award for her performance as Ella in the Off-Broadway play
Deep Blue Sound by
Abe Koogler. ==Personal life==