The troupe began as live radio performers in Los Angeles, California on radio stations KPPC-FM and KPFK during the mid-1960s.
The group's name is an astrological reference: The membership comprises all three "fire signs," born under Aries (Austin), Leo (Proctor), and two under Sagittarius (Bergman and Ossman). It is also a parody of Fireside Theatre, an early television series that ran on NBC from 1949 to 1955, followed by Jane Wyman Presents the Fireside Theatre (1955-58); it may also be a reference to the "Fireside Chat" radio shows of Franklin Delano Roosevelt, a parody of which can be heard in one of the Theatre's Nick Danger adventures.