08/12/2011 at 08:00 AM EDT
Music fans were shocked when Kings of Leon abruptly abandoned a concert after 11 songs and canceled their U.S. tour
, citing "vocal issues and exhaustion" while alluding to mysterious internal sicknesses
within the band.
But just a few hours earlier, PEOPLE had sat down with the Grammy-winning band for its last interview before the meltdown and found that dysfunction has long been a part of their deep bond and success – and what hasn’t killed them has made them stronger.
A new documentary, Talihina Sky: The Story of Kings of Leon
, which airs Aug. 21 on Showtime, also offers a no-holds-barred look at what lead singer Caleb Followill, 29, tells PEOPLE is "the good, the bad and the ugly," from their drunken fights and drug use to emotional revelations about drummer Nathan, Caleb and bassist Jared’s humble beginnings traveling from church to church with their Pentecostal preacher father (their cousin, guitarist Matthew was raised in the same faith in Mississippi).
"A band's normal struggles are when one guy's doing drugs and the rest of them are not," says Caleb, whose vocal problems were cited after the truncated concert. "When we did drugs or drank, we did it together. The only struggle for us was it took us four records before people took us seriously in this country."
For more revelations from the band's final interview the day of the Dallas debacle, the new documentary and more, pick up this week's PEOPLE, on newsstands Friday