"Stanley was fond of titles in search of screenplays," Frewin says. "And Dr. Jazz was such a rich subject—the contrast of what was going on in the camps, on the Eastern front, and yet here was a German officer who was having a good time listening to jazz. Stanley was also drawn to what this said about music and its ability to unify people and transcend even rigid political differences."

While a script for Dr. Jazz never materialized—and the project was later shelved, in part due to Aryan Papers, a film set in occupied Poland that Kubrick abandoned in the mid-'90s despite an intensive preproduction—Zwerin's research remains engrossing today.

Though stationed in Paris for more than 20 years as the jazz critic for the International Herald Tribune, Zwerin never acclimated. "I consider myself on loan, like a Picasso," he writes in Swing. "One year led to another and now I find myself without a place to hang." Parisian loneliness had become "literally breathtaking, a gasp not a gas." Seeking refuge, Zwerin traveled the continent collecting interviews with the jazz preservationists who gathered in basements and backrooms during occupation, and filed their reminiscences in the IHT, among other publications. (Swing is a collection of his columns that reads like a collage, with digressions upon digressions.)

Zwerin is at his best when conversing with musicians—at one point he even brandishes his horn for a post-interview blowing session—but the more surreal findings come from encounters with the occasional toe-tapping retired Nazi officer. In the skies over London, we learn that a Luftwaffe ace tuned into the BBC while crossing the Channel, hoping to catch a few bars of Glenn Miller before bombing the radio antenna. On the ground, when the Royal Air Force rained bombs on Vienna, a trombonist in a Nazi swing band "would stick his trombone out the window and play 'St. Louis Blues' instead of hiding in the cellar." (In order for that particular jazz standard to pass muster in Vienna, the title was first changed to "Sauerkraut.")

Throughout the book's mere 200 pages, Zwerin unearths lost notes from the underground. A Django Reinhardt record was worth two kilos of butter on the black market. A German objector fondly recalls scoring the plum assignment of tracking down the cream Louis Armstrong preferred for his chapped lips; the brand was available only at pharmacies in Berlin. Upon receiving the shipment of lip salve, which was smuggled Stateside through a Paris club owner, Louis mailed his unknown German aid a personal letter of thanks.

Not all accounts are as lighthearted. Zwerin mourns the Jewish musicians who clung to life by entertaining guards in concentration camps, and those on the run, like Eric Vogel, a Czech jazz trumpeter who soaked his valves in sulfuric acid when Nazis invaders began confiscating instruments. The acid served "to keep anyone from playing military marches on a jazz trumpet." In a 1961 article for Down Beat, Vogel claims his life was spared during a ghetto roundup when an SS officer who had eavesdropped on one of his jam sessions recognized him at headquarters and escorted him home, borrowing some of his jazz records and books as compensation. In Frankfurt, musicians wandered the streets whistling "Harlem"—if a fellow musician recognized the tune, he whistled back.