Ella Peterson works in the basement office of Susanswerphone, a telephone answering service. She listens in on others' lives and adds some interest to her own humdrum existence by adopting different identities for her clients. They include an out-of-work Method actor, a dentist with musical yearnings, and in particular playwright Jeffrey Moss, who is suffering from writer's block and desperately needs a muse.

Judy Holliday
as Ella Peterson

Dean Martin
as Jeffrey Moss

Fred Clark
as Larry Hastings

Eddie Foy Jr.
as J. Otto Prantz

Jean Stapleton
as Sue

Ruth Storey
as Gwynne

Dort Clark
as Inspector Barnes

Frank Gorshin
as Blake Barton

Ralph Roberts
as Francis

Valerie Allen
as Olga