"Lucky" Garnett (Fred Astaire) is tricked into missing his wedding because he believes his trousers to be out of fashion, and is required to earn $25,000 in New York City before the girl's father will allow the marriage to take place, only Lucky doesn't earn money as much as he wins it. By chance he runs into Penny Carroll (Ginger Rogers), a dance instructor who wants nothing to do with him until she finds out that against all odds Lucky is a fantastic dancer. Eventually they fall in love and she gets engaged to a band leader, but the marriage is averted when he falls for the same trouser con.
The main draw for Swing Time, other than the roulette games, is the dancing chemistry between Fred Astaire and Ginger Rogers. They don't disappoint. Director George Stevens frames the sequences in a continual long shot, which was probably standard at the time, but in retrospect seems like a novel approach. It allows us to watch the artistry of the dance without wondering if they've used a body double for the shots of the feet or employed other such tricks of the editing booth.
It's interesting to note that we don't see Astaire and Rogers fall in love in a typical way, rather they fall for each other on the dance floor. Most of the honest communication happens while they dance, for that matter. There are times it seems they're making love simply by tapping their feet. It's a beautiful thing to watch.
For a musical, Swing Time doesn't contribute a whole lot to the American songbook. Only one song, "The Way You Look Tonight", has had any lasting appeal, and you could make the argument that Frank Sinatra's recording had a great deal to do with that. The song runs throughout the film in a recurring motif, often creating a segue between a lesser song and the subsequent dialogue and reminding us just how inferior the song we just heard really was.