A new infection that simply makes people feel happy is treated as a threat by the authorities while its "victims" work to spread it to others.

George Peppard
as Pete

Mary Tyler Moore
as Liz

Dom DeLuise
as J. Gardner Monroe

John McMartin
as The Mayor

Nathaniel Frey
as Conrad

Charles Lane
as Dr. Shapiro

Jeanne Arnold
as Gertrude

George Furth
as Murgatroyd

Morty Gunty
as Sgt. Gunty

Joe Ponazecki
as Officer Ponazecki