Richard Barrios calls it that "bump" moment - the pivot point in a film when the characters who have thus far been chatting, spatting, courting and carousing just like normal folk burst into song. Suddenly they're no longer in the real world, but on a plane of existence where an orchestra can swell out of nowhere, where average Joes and Jills sing while showing off their waltz moves, their tap skills, their synchronicity with a line of high-kicking chorines.
It's the movie musical, that strange beast that - when done right - can be sublime, transcendent, inspiring.
Barrios, a film historian with an affinity for the wildly diverse song-and-dance genre, offers a readable, authoritative meditation on the Hollywood musical.
From its nascent days, during the tumultuous transition from silent cinema to talkies, to new hits and misses such as Rent (2005), Sweeney Todd (2007) and Mamma Mia! (2008), he notes the through lines, the breakthroughs, the anomalies, the crises, the trends, the stars.
Musicals, he writes, are the most "conspicuous" of movie categories - whether you love 'em or hate 'em, by their nature they call attention to themselves. "Their risks are as amplified as their budgets and soundtracks, their fiscal and aesthetic stakes are high, and they stand out as much when they fail as when they succeed."
In a chapter on the finances of the movie musical ("With Plenty of Money"), Barrios talks about the alpine numbers for The Sound of Music (1965), the belated box office magic of The Wizard of Oz (1939) - a flop on its initial release, but a poppy field of fortune ever since.
Dangerous Rhythm will probably find its most avid readers in that TCM-watching, Rocky Horror Picture Show singalong-ing crowd already familiar with the subject. But if you've never seen Love Me Tonight, Rouben Mamoulian's 1932, Maurice Chevalier and Jeanette MacDonald rom-song, that's what Netflix and YouTube are for.
Barrios knows this business inside and out, upside and down. He can turn a spiffy phrase and even his footnotes are fun. About Chicago's decade-long trip to the screen, he writes: "[Choreographer] Bob Fosse actually set up a meeting with Madonna to discuss a possible Chicago movie. That he died on the day this was supposed to occur surely qualifies as tragedy. Possibly also as a tragedy averted."
Some may argue with the esteem (or lack of same) in which he holds certain titles, but that's the author's right, and there's very little else to argue with in this provocative, wide-ranging book. Clearly, musicals do matter - back in the day (any day), and here and now.