Gavin Poolman remembers using the film cans containing the only existing work prints of "Festival Express" for hockey goals. His parents were divorced, and his father, who was the original producer of the film, moved often. Young Poolman never could understand why his father insisted on lugging around this stupid collection of heavy film canisters. At one point, he dragged the cans out of the garage and stacked them in the street to serve as goalposts.

But in the mid-'90s, after he grew up and went into the film business in London, Poolman was contacted by a film researcher from Canada who was trying to find the footage, and Poolman knew exactly where to look.

"He'd found the negatives to this stuff," Poolman said. "Apparently he'd been looking for it for years."

"Festival Express," which will have its world premiere tonight at the UA Galaxy (followed by a party at the Great American Music Hall), is rock's great lost concert film. The movie, which opens its theatrical run July 23 at the Bridge, features a cast of 135 drunken and deranged rock musicians -- including Janis Joplin, the Grateful Dead, the Band, Delaney & Bonnie, Buddy Guy, Sha Na Na and others -- rolling across Canada on a train in 1970, partying nonstop in between mini-Woodstock performances at outposts along the way.

The film not only captures extraordinary work by Joplin, only months before her death, and the Band and the Dead at their creative peaks, but comes crackling to life in scenes shot in the train's jam-packed bar car, like Rick Danko of the Band howling in Joplin's amused face while Jerry Garcia noodles along with the drunken fracas.

The festivals proved to be financial disasters from day one. And the film, started by Poolman's father, Toronto film distributor Willem Poolman, disappeared almost before the last musical note stopped ringing. Cameramen took their work home to hold hostage for promised paychecks. The beleaguered festival promoters, who banned Poolman from the train, claimed rights to the footage. A court order was issued to keep Poolman from developing the film. At one point, he was hiding film in a meat locker.

Of the 75 hours of footage shot, Gavin Poolman, who signed on as producer of the movie his father started, eventually recovered 46 hours of 16mm film. Film researcher Garth Douglas, who contacted Poolman about the project, discovered much of the missing footage in the Canadian Film Archive, where it had been deposited by someone associated with the production more than 30 years ago.

What started it all was a little-known footnote to the '60s rock festival era. Canadian concert producers Ken Wallace and Thor Eaton booked stadiums across Canada and transported the rolling rock festival from concert to concert via private railcars. Tickets were priced sky high to cover the extravagance, and protesters who believed that music should be free virtually shut down the concerts. The Toronto opener played to a slender crowd in the stadium, while the cops held back angry demonstrators across the street and the Dead agreed to perform for free later across town. A planned Vancouver show was canceled, but the festival went forward with the five-day train trip to Calgary, playing to half-empty houses along the way.

The train itself was a beehive of endless jamming and much fraternizing. Deprived of their customary refreshments by having to travel across international boundaries, the usually drug-addled musicians turned to alcohol. They quickly drank the train dry, then took up a collection, stopping the locomotive in its tracks across the road from a Saskatchewan liquor store and buying out the store's inventory.

"Drugs arrived when they got to Winnipeg," "Festival Express" director Bob Smeaton said. The event was little noted at the time -- although Rolling Stone chronicled the bacchanal as "The Million Dollar Bash" -- and quickly forgotten. Film researcher Douglas picked up the trail decades later, having heard tales of this "Canadian Woodstock." Gavin Poolman, who also produced the 2000 Balkan civil war drama "The Zookeeper," raised $3 million and hired Smeaton, a rockumentary veteran who served as series director for "The Beatles Anthology."

The original cinematographer, Peter Biziou, went on to win an Oscar for "Mississippi Burning," so there was some native talent behind the lens in the first place, although there was no end to the technical problems on the project. Veteran engineer Eddie Kramer, famous for his work with Jimi Hendrix, was brought in to mix the audio tapes. The film had to be blown up from 16mm. Film and audio were recorded at different speeds; without modern digital technology, the movie probably never could have been made.

"They would have never been able to get this film to work," director Smeaton said of the earlier attempt to make the movie. "The cameramen were so stoned, it was hard to get the film right at all."

The cameramen accidentally break into the scenes. Microphones protrude into the frames. Even with five cameras on the crew, Smeaton still couldn't put together a complete version of Traffic playing a 15-minute version of "Feelin' Alright," captured brilliantly on audio, because all the cameras ran out of film. One cameraman told Smeaton confidently that he remembered shooting a particular scene himself, only for Smeaton to spot the guy in the footage standing in the crowd not filming anything. When Smeaton came to San Francisco to interview the surviving members of the Grateful Dead for the movie, Phil Lesh didn't remember there being cameras at all.

Gavin Poolman, who was a young boy at the time of the festival, remembered the project well. It was not just those film cans his father was forever shuffling around from garage to garage. He associated the abortive movie with his parents' divorce, which coincidentally happened around the same time, and moving out of their nice big home that his father could no longer afford. When his father's basement flooded one winter, he saw the film cans crusted with ice. But, in fact, when the movie was finally made, those work prints supplied some valuable footage the filmmakers couldn't find anywhere else.

Today Willem Poolman is an 80-year-old immigration attorney in Toronto who still goes to the office every day. He got into the film business by accident in the '60s, distributing foreign films and independent releases while still working as an attorney. His success with rock films such as "Monterey Pop" led him to make "Festival Express," although he found himself at odds with the festival producers almost from the start. Banished from the train, Willem Poolman remembers handing film stock to his camera crew from an overpass in Winnipeg as the train passed beneath.

He long ago gave up the film business, but if he had given up the idea that his movie would ever be made, why did he keep all those film tins?

"Until I saw the results, I would have never believed it," he said. "I really had the feeling it needed to be made. That's why we did it. It had to come out. It was fun doing it like this."