Marion Haines is a small-town girl from Wyoming with big dreams of singing with a band. She moves to Los Angeles in pursuit of that dream and unwittingly runs afoul of the mob.

Now Bugsy Siegel wants her dead. And Bugsy always gets what he wants.

Beginning at opposite ends of the country, And the Angels Sing tells the parallel stories of an up-and-coming young singer named Marion Haines, and popular big band trumpeter, Teddy Williams. They don't know each other, but like two freight trains converging on the same track, Marion and Teddy are destined to meet head-on in a collision that will put their courage to the test.

In her quest to sing with a popular big band, Marion signs on with over-the-hill bandleader Buddy Baldwin, and largely because of Marion, Baldwin's band lands a gig at the popular Club Playa del Mar in Long Beach, California. The club's owner, Johnny Angelino, takes a personal interest in Marion with more on his mind than helping her singing career. Marion naively accepts Angelino's help, unaware that he is in cahoots with gangster, Bugsy Siegel.

She learns the terrifying truth about her benefactor when, in the wrong place at the wrong time, she overhears a conversation between Angelino and Siegel that could send Bugsy to the electric chair. But by then her fate was sealed. Siegel orders Angelino to take Marion for a ride. While waiting for Angelino to carry out Bugsy's orders, Marion bravely escapes and hides on Santa Catalina Island, where her big brother manages the Avalon Casino Ballroom.

At the same time, Bobby Ross, the number one bandleader in the country and Teddy Williams' employer, wraps up a record-breaking engagement at New York's Paramount Theater and sets off on a cross-country tour that ultimately takes Teddy to the Avalon Casino. That's where he meets Marion and suddenly finds himself embroiled in her flight from Siegel and the mob. The chances of them escaping Siegel's wrath depend entirely on their ability to outwit Bugsy's henchmen and the street savvy of an aging homicide cop named O'Rourke.