Ghostbusters centers on three university researchers (Bill Murray, Dan Aykroyd, and Harold Ramis) of paranormal activity who go into business of their own once they get into trouble for their uncouth antics, and their grant money runs out.  They emerge on the scene as the "Ghostbusters", a trio of exterminators (of sorts), willing to investigate phenomena from anyone in New York City willing to call their number and pay their fees.  Though the public is initially skeptical, these men soon become heroes, then celebrities, for their success rate, drawing the attention of the media, as well as the EPA (who are curious about their containment system), as the amount of ghostly appearances seems to be on a major upswing.
Sigourney Weaver co-stars as a cellist named Dana Barrett, who is one of the first in her old building to begin seeing strange things in her refrigerator, causing her to make the call she never thought she'd have to make.  Along with her neighbor, Louis Tully (Rick Moranis), she becomes the conduit for the rise of the malevolent Babylonian spirit, whose aims are to bring darkness onto the world. Directed by Ivan Reitman.
 

Erratum: The artist friend Aykroyd used for conceptual art on Ghost Smashers was John "The Viking" Deveikis, not the cited Thom Enriquez, who made additional conceptual art once Reitman was on board.