Of Golden Age musicals, 42nd Street is about as close to the archetype as they come. It’s about an hour of exposition as a big Broadway director puts on his last big show (as he’s ill), and all manner of catastrophes befall him en route to opening night. Most notably in 42nd Street, his star breaks her ankle and has to be replaced by a chorus girl. Then comes the music and dancing, rapid fire. While ‘Shuffle Off to Buffalo’ is the sentimental favorite musical number, it’s the title song and dance number, about 20 minutes of insanity that takes place largely on an enormous lazy susan, that really gets things moving. Too bad it comes right at the end.