Following her movie debut with Elvis Presley in Loving You (1957), she made 10 films in five years, including Wild Is the Wind (1957), King Creole (1958), and Where the Boys Are (1960).

At the height of her career, Hart left acting to enter the Abbey of Regina Laudis monastery in Connecticut.

Hart decided to become an actress after visiting her father on movie sets, including the film Forever Amber.

[5] Her grandfather was a movie theater projectionist whose enthusiasm for films influenced her decision to pursue an acting career.

[4] Hart starred in the lead role of Lisa in The Inspector, which was based on a novel by Jan de Hartog, and nominated for a Golden Globe for "Best Picture – Drama".

Hart played a Catholic missionary, who against all warnings risks her life to honor both her vows to God and her desire to continue her dead husband's work to help a community of poor and sick embattled Indian tribes.

[8][9][10][11] While Hart was making Francis of Assisi in Rome, she met Pope John XXIII, who was instrumental in her vocation.

In April 2006, she testified at a Washington congressional hearing on the need for research of the painful and crippling disease amid her ordeal.

[15] Hart was instrumental in developing the Abbey of Regina Laudis's project of expansion of its community connection through the arts.

Hart's vision was the development and expansion of the abbey's open-air theater and arts program for the Bethlehem community.

[13] Hart was named prioress of the monastery in 2001, after the election of Mother David Serna as second abbess of Regina Laudis, and held that office until 2015.

Hart's autobiography, The Ear of the Heart: An Actress' Journey from Hollywood to Holy Vows (Ignatius Press), co-authored with Richard DeNeut, was released on May 7, 2013.