Mike McCready (Pearl Jam) and Barrett Martin (ex-Screaming Trees) discuss the Mad Season reissue, late bandmate Layne Staley and more.

Pearl Jam's Mike McCready says the unexpected new expanded reissue of "Above" from Mad Season, his mid-90's Seattle supergroup alongside Alice in Chains' Layne Staley and Screaming Trees' Barrett Martin, shines with new lyrics from the ex-Trees' singer Mark Lanegan and a guest turn from R.E.M.'s Peter Buck, but that it owes its existence to bittersweet serendipity.

"Eight months ago in our Pearl Jam vaults," McCready tells Billboard he found "tucked away in a corner was this Mad Season live at the Crocodile [in Seattle in 1995] tape. I forgot that we had recorded that, and that was our record release show. I thought, this is pretty good. " He adds that while "it was very painful to listen to it because [Staley and bassist John Baker Saunders] had died" only a few years after it was recorded, "that sparked me."

The three disc "Above" re-issue, due April 2 on Sony's Legacy Recordings (iTunes pre-order available), features the Mad Season's 1995 album, a DVD featuring what drummer Barrett Martin remembers Buck calling the "super heavy blues" group's Dec. 31, 1994 and April 29, 1995 shows at Seattle's RCKNDY and Moore Theater and more, plus five bonus tracks that include three previously unreleased songs with recently penned lyrics and vocals by Lanegan.

The music for "Locomotive," "Black Book of Fear" (co-written by Buck) and "Slip Away," the three songs Lanegan has newly finished, began life during 1996 sessions intended to become a second Mad Season album called "Disinformation" that never came to fruition because Staley and Saunders "were getting hard to get ahold of," says McCready. "You can only try so long before you kind of go, ok we need to move on or figure something else out. We tried hard to get them down but they weren't in any shape."

In 1999 and 2002 respectively, both Saunders and Staley died of heroin overdoses. "'Slip Away,' which I wrote, was kind of my feeling at the time how [Mad Season] was slipping away," McCready says. "The guitar solo at the end of that, you can hear the pain that's in that. That's my pain of how this whole thing was all falling apart when Baker and Layne were dying… Mark put lyrics to that and they mean something different now… but I'm getting a little deep in to what the lead is. You'll listen to it and you'll hear pain."

While McCready feels that the new Mad Season package "is a little snippet of history, it's like a time capsule of that time." He also says that Lanegan's involvement has brought everything into the present. "I've always felt over the last 16 years that the only person who could ever do this justice was Mark Lanegan," McCready says. "He finally came around… I got [the new songs] back and they sound awesome."

"The original plan when we were working on that second record was that Mark was going to be much more involved in co-writing songs and this is what Layne wanted," Martin says. When the reissue idea surfaced, "we sent him all 17 basic tracks… I said, 'here's what we have, is there anything on there you felt compelled to write some lyrics and sing on. And he picked three! More than we expected."

"I don't want to speak for Mark, because they're his words, but it's his tribute to Layne and Baker. He knew those guys very well. He was one of Layne's best friends," says Martin.

For McCready, who says he will be very busy finishing Pearl Jam's next album in the coming months, Mad Season has had an impact in his Pearl Jam work. "I had more confidence to write songs directly because of that [1995] Mad Season record," he says. "Out of that came [Pearl Jam's '90s songs] 'Given To Fly' and 'Faithful.' "

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"I hold Mad Season very fondly to my heart and there's a lot of sadness in that too," McCready concludes. "There's also something that makes me grateful that people have gravitated toward [it] over the years. It is very bittersweet."