In the late-'60s and early-'70s, New York's Blood Sweat & Tears had a string of soulful, horn-punctuated hits including "Spinning Wheel," "You've Made Me So Very Happy" and "And When I Die." But by 1972, the hits had dried up. Why? In 1970, at the height of their popularity, the socially conscious band agreed to go on a tour of Eastern Europe that was sponsored by the US State Dept. With the very unpopular Vietnam War still raging, the band were ridiculed for working with the Nixon administration and they were never able to regain a foothold.

But there's a lot more to the story than that. It turns out the band were coerced by the Nixon administration to go on the tour, as explained in an upcoming documentary by John Scheinfeld (The U.S. vs. John Lennon, Who Is Harry Nilsson [and Why Is Everybody Talkin’ About Him]?What The Hell Happened To Blood, Sweat & Tears? “John Scheinfeld is a unique combination of filmmaker, historian and detective,” says BS&T’s Bobby Colomby. “He asked me a simple question: ‘What the hell happened to Blood Sweat & Tears?’ My convoluted answer somehow ignited an engine inside of John that was the beginning of an unexpected adventure: creating a documentary film to reveal the answer to this decades old question. This won’t be your typical music doc, in any way, shape or form.”

The meat of the documentary comes from 65 hours of rare footage from Blood, Sweat & Tears' "Iron Curtain Tour," where they played Communist Yugoslavia, Romania and Poland, and also involves the "FBI, CIA, Immigration and Naturalization Service, Republicans and Democrats and the secret police of three nations."

Scheinfeld is still working on the film, but he's shared a work-in-progress clip featuring Jim Fielder, the band's bass player, speaking at a State Department reception before the tour began, as well as footage of Colomby and guitarist Steve Katz talking politics with students in Yugoslavia, as well as performance footage from the tour. Watch that below.