Martha Campbell Plimpton (born November 16, 1970) is an American actress, singer and former model. Plimpton is a screen, stage and television actress. She first appeared as Jonsy in the feature film The River Rat (1984) before rising to prominence in the Richard Donner film The Goonies (1985) portraying the character Stef. She then appeared in The Mosquito Coast (1986) portraying Emily Spellgood. Plimpton's role garnered her further success within the feature film industry. Throughout her career Plimpton has appeared in many feature films, including critically successful films Running on Empty (1988), Parenthood (1989), Eye of God (1997), The Sleepy Time Gal (2001), Hair High (2004) and Small Town Murder Songs (2011).