In Sing a Jingle, Allan Jones plays popular radio crooner Roy King, who goes to work in a war plant after being declared 4F. He falls in love with Muriel Crane, the boss' daughter, who is at first unaware of the fact that King is the heartthrob of millions (he's gotten the job under an assumed name).

In this WW II musical, a young man suddenly finds himself in charge of his family when his father is called to war. To help the flagging spirits of local factory workers, the plucky lad, his siblings and his schoolmates put on a lively little show. With a little work, he even convinces Count Basie to come with his band.

As sixteen year old Ann Winters begins a relationship with an older actor to further her career, lookalike fan Penelope Ryan is recruited by a group of former child stars to perform in a USO show.