At the loss-making Surf and Sand Playhouse in Cape Cod, introduced to us by a jaundiced Press Agent Seating capacity 640, number of spectators per night 14, a group of young apprentices complain of their exploitation by the owner Seymour Fleming, who is even threatening to cancel their own planned revue. Their leader Valentine (Val) White has written a song about it. They are determined to do the show for the sake of the theatre's down-trodden co-owner Bunny Byron, who has to work for Fleming because of the money her father owed him. Terry and Gus have a love-hate relationship, not improved when Terry tries flirting with Lee Calhoun, the insufferable author of The Deep North, the play in rehearsal.
Val falls for the glamorous Jennifer Owen, the juvenile lead in the play, and his feelings are soon reciprocated. She sneaks away from her dominant mother Phyllis to watch Val rehearsing the revue. A passionate embrace is interrupted by young Susie, who is crazy about Val and jealous of the glamorous arrival. Val sees Susie as a younger-sister type, but for her he is "My Funny Valentine."
Jennifer can't stand Lee's play, his writing or his hammy acting and threatens to quit, but Phyllis imperiously solves the issue: a second week's run of the play, the first to count as rehearsals and no time at all left for the apprentices' revue. Jennifer backs down, but the kids and Bunny - are going to fight it all the way
At the start, the Press Agent indicates a mood of depression and resignation among the kids: Susie alone is optimistic, but Val is upset that Jennifer has let them down. Lee arrives, hunting for Jennifer, who has slipped the leash again - the kids inveigle him into the cellar and lock him in, but he escapes, only to overhear Jennifer, who has come to tell the kids that she is planning to fake sickness to get out of the play and he slinks off to tell Fleming.
Phyllis, also looking for Jennifer, dramatically accuses Bunny of not being a lady for refusing to help search, which Bunny cheerfully admits. Fleming announces that the boy-wonder producer Steve Edwards (who is known to 'have a thing' for Jennifer) is coming to see the play, whereupon Susie and Terry hatch separate plans ..........
In Steve's hotel room, both girls are caught by Gus, who bundles Terry out, but Val gets a shock when he bursts in on Steve and Susie - not realising that they are brother and sister (and they're not telling yet!) He leaves in righteous fury, which delights Susie - but uppermost in her mind is getting her brother to see the revue.
The apprentices mischievously succeed in turning The Deep North into a shambles of miscued entrances, sound effects and collapsing props, and sneak off to the barn to do the revue, where Steve joins them. Of course, Fleming finds them, but is out of time in firing them all, as Steve has just handed them a cheque to option their show, so Fleming gets the debt paid off, Val and Susie are reunited - as the Press Agent says at curtain "A musical comedy can have a happy ending!"