It was supposed to be a book signing for Alice Cooper bassist Dennis Dunaway's autobiography, "Snakes! Guillotines! Electric Chairs! My Adventures in the Alice Cooper Group."

Which would've been a cool enough event for any fan of Cooper's early work with the bandmates who entered the Rock and Roll Hall of Fame in 2011 on the strength of such classics as "I'm Eighteen" and "School's Out."

RELATED: Alice Cooper bandmates reflect on their historic past.

But the owner of the Dallas record store where Dunaway's signing was scheduled to happen – Chris Penn of Good Records – had chosen that date in October 2015 for a reason.

He knew Cooper had the day off from touring in Texas.

And as Penn explains in the documentary/concert film that made its world premiere at the Phoenix Film Festival, picking up best documentary short in the bargain, "Alice knows where the good golf courses are in Dallas."

That's how Penn managed to pull together a headline-grabbing reunion of the four surviving members of the legendary group whose 1973 U.S. tour in support of the chart-topping "Billion Dollar Babies" album broke box-office records held by the Rolling Stones – Cooper, Dunaway, guitarist Michael Bruce and drummer Neal Smith.

"I was gonna go sign books and do a Q&A on my own," Dunaway says. "And then we found out that Alice was going to be in town and have a day off, so Chris asked if Michael and Neal would be interested in playing and we ended up turning it into this massive event around the book signing. Now here we are in 2019, releasing the film of it."

INTERVIEW: Dennis Dunaway on life with Alice Cooper

'Alice Cooper: Live From the Astroturf'

The concert, as captured in “Alice Cooper: Live From the Astroturf," starts with Bruce on lead vocals for "Caught in a Dream." Then, Cooper makes his entrance with guitarist Ryan Roxie of his touring band and joins his former bandmates in a raucous trip down memory lane, from "Be My Lover" to "I'm Eighteen," "Is It My Body?," "Under My Wheels," "No More Mr. Nice Guy," "School's Out" and "Elected."

“It was very spontaneous, I thought," Bruce says. "In a record store packed with people who didn’t really know what was happening. They showed up and we played. And they were blown away. Neal and Dennis and I were scheduled to be there for the signing and then after, we got up on stage. That's when it started getting crazy and magic.”

Even though they hadn't played together for a while, Bruce says, "It's always fun. It's like putting on an old comfortable pair of shoes or getting on a bicycle. You don't think about it. You just go with it."

It's a stellar performance and the sound is great. Or as Dunaway says, "Not bad for no rehearsal and having not played those songs in quite a few years. The night before, Neal, Michael and I got together and made sure the amps were working and stuff. We ran over some stuff, but we were trying to focus on the technical things, making sure all the microphones were the volumes we wanted and all that. It was more like a soundcheck than a rehearsal, but you know, it’s not like we haven’t played those songs before."

They hadn't done "Elected" in awhile, though. Roxie, who was filling in on guitar for the great Glen Buxton, who died in 1997, talked them into doing that one.

"We hadn’t played that in a million years," Dunaway says. "Neal said he hit the first crash on the opening chord of the song. Then he said to himself 'What happens next?'”

Dunaway laughs, then adds, "But it came out great. For one thing, we were all just having such a blast and things fell into place. As soon as you hear Neal start playing and Michael and Alice and everybody. Ryan Roxie was great, too. He sat in for Glen. But as soon as you hear the original sound and all of the parts being played the way they were written, it makes things kind of fall into place naturally."

Other Alice Cooper reunions

That show led to other opportunities for Cooper's former bandmates, including two reunion tracks on Cooper's latest album, "Paranormal," a U.K. tour and an industry event in Nashville in 2017 (which led to Cooper also having them onstage to take part in the encore at his Nashville concert).

RELATED: Alice Cooper on 'accidental' concept album 'Paranormal,' reunion with '70s lineup, Bob Ezrin and more

"We did five cities in England, including 14,000 people at Wembley," Dunaway says. "That’s the first time we played Wembley since 1972, when we stalled the flat-bed truck with the picture of Alice with only a snake keeping his humility in order, the photograph that Richard Avedon did. We had this giant photograph. And then the truck accidentally broke down right in the intersection in one of the busiest intersections in London and we sold out Wembley in one night."

The original members went their separate ways after "Muscle of Love" in 1974. Cooper launched his solo career a year later with "Welcome to My Nightmare."

The four surviving members reunited in 1999 at the second Glen Buxton Memorial Weekend at CoopersTown in Phoenix and played Cooper's Christmas Pudding with Steve Hunter on guitar in December 2010 at the Dodge Theatre.

"When we were rehearsing for that in Phoenix, they came in and stopped us from rehearsing," Dunaway recalls, "to announce that we had been inducted to the Rock and Roll Hall of Fame. And the next night, when we played the Pudding show, Bob Ezrin came out and announced it to the crowd."

They reunited again at the Rock and Roll Hall of Fame induction ceremony the following March and again a month later to play the Revolver Golden Gods Awards and record a live set for a Jägermeister Ice Cold 4D webcast.

As Dunaway explains that last event, "We holographically did this show at the Battersea Power Station in England. You know the factory-looking place that’s on the cover of the Pink Floyd ‘Animals’ album with a pig hanging down? We recorded the show in LA and then they had a holographic projection of us onstage at this big event for Ice Cold Jagermeister. They did all these special effects where we were inside these blocks of ice."

They also appeared on three tracks on the "Welcome 2 My Nightmare" album in 2011.

The Dallas record store concert was the first they'd played together since those events in 2011.

"It always was a blast and it continues to be," Dunaway says. "You know, as soon as we’re together, we’re all in high school again."

A legend born at a Phoenix high school

Cooper, Dunaway and Buxton made their first onstage appearance in the Cortez High School "cafetorium," shaking the wigs they'd bought at Woolworth's while spoofing the Beatles as part of a talent show.

By the time they hit the Phoenix club scene as the Spiders, they'd recruited Bruce, a North High football player, scoring a regional hit with a single called "Don't Blow Your Mind."

After changing their name to the Nazz, they moved to Los Angeles in 1967, where Smith, a Camelback High grad who'd been in art classes with Dunaway, Cooper and Buxton at Glendale Community College, joined on drums.

They have a lot of history. And they've shared a lot of laughs.

"Humor has always been the glue that’s kept everything together through thick and thin," Dunaway says. "We miss Glen’s humor, though. He was sharp-witted. The guy that you knew if you left the room, when you came back, that he had whittled you apart while you were gone."

He laughs, then says, "But it was like a Don Rickles kind of thing where everybody was a target. So you couldn’t take it personally. Michael has this great offbeat humor. I have this very abstract humor and Michael does, too. For instance, somebody took a photograph of the band once and they took a long time to get the focus and everything and I said, 'I could’ve done an ice sculpture by now' and Michael said, 'Are you a cubist?' And then, Neal’s just got this great, goofy sense of humor where he turns into goofy characters from time to time. It’s very Ohio. I’m married to Neal’s sister and she’s got that same type of humor."

There's a bittersweet side to reuniting with your high school friends.

As Bruce says, "Sometimes it’s hard for me to strike up a conversation with Alice. He’s so busy and what am I gonna talk about? 'Oh hey, guess what? I mowed my lawn last week.' He’s out on the road constantly, doing a lot of things. But he’s a great guy. I just wish we could do these kind of things more often."

It's clear from watching Cooper rock the record store with his old friends that he's enjoying the experience as much as they are.

As to what the future hold in terms of further dates with Cooper, only time will tell.

As Dunaway says, when he and Cooper get together usually "we’re just so happy to be together that we don’t turn it into a business thing."

He'd love to do more playing with his former bandmates, though.

"We’ll see," he says. "I mean, we’re all friends. We always have been. And if the opportunities arise, Michael and Neal and I (and Glen when he was alive) were always ready and willing to work together. All it takes is a phone call and we’re ready."

“Alice Cooper: Live From the Astroturf"

When: 7:50 p.m. Friday, April 5.

Where: Harkins Scottsdale 101, 7000 E. Mayo Blvd.

Admission: $15-$25.

Details: 480-513-3195, phoenixfilmfestival.com.

Reach the reporter at ed.masley@arizonarepublic.com or 602-444-4495. Follow him on Twitter @EdMasley.

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