Harold Ryan is a Hemingway-styled hunter and explorer who disappeared in 1962 while on an expedition to the Amazon rain forest with his sidekick Looseleaf Harper (the pilot who dropped the atomic bomb on Nagasaki). Finally resigned to her husbands death after eight years, Penelope Ryan and her twelve-year-old son Paul resume their lives in their Manhattan penthouse apartment where Penelope is being courted by two suitors, peace-loving Dr. Norbert Woodly and hawkish vacuum cleaner salesman Herb Shuttle. When Harold unexpectedly walks in the front door one night in 1970 (with Harper in tow), he expects life to simply pick up where it left off. He is appalled to discover that his wife and the world at large have changed considerably in his absence.
Interspersed throughout the play are discourses about life in heaven and the joys of playing shuffleboard in the afterlife, delivered by Harold's alcoholic third wife, Mildred; ten-year-old Wanda June and Nazi officer Siegfried von Konigswald (the Beast of Yugoslavia), killed by Harold Ryan during the second world war.
Of the original Broadway production, Newsweek's Jack Kroll wrote:
Almost every time an American novelist writes a play he shows up most of our thumb-tongued playwrights, who lack the melody of mind, the wit, dash and accuracy of Saul Bellow and Bruce Jay Friedman. And the same thing must be said of the writing in Happy Birthday, Wanda June, . . . Vonnegut's dialogue is not only fast and funny, with a palpable taste and crackle, but it also means something. And his comic sense is a superior one; Wanda June has as many laughs as anything by Neil Simon.