By Michael Cerio

PHILADELPHIA (CBS) — In 2015, as Philadelphia prepared for the Pope, the satanic songs of Ghost prepared to reschedule.

The Swedish heavy metal band, shrouded in satanism and secrecy, found their show inside the off-limits “traffic box” reserved for the papal visit and were forced to move to a later date.

“Philly wasn’t big enough for the two of those dudes, so unfortunately we had to give in,” laughs one of the band’s Nameless Ghouls over the phone earlier this week.

The band moved that show to the following week and has been on the move upward ever since. Ghost won a Grammy in 2016, topped the rock charts with their single “Square Hammer,” and are set to open for the legendary Iron Maiden for The Book Of Souls Tour 2017. They stop back in Philadelphia on Sunday, June 4 at the Wells Fargo Center.

“I’m very excited about it,” he explains about the bands trek with Iron Maiden. “Of course. One of my childhood favorites, and now as a grown man their also friends of ours and good mentors.”

Ghost is a band that is heavy on theatrics and anonymity with all members shielding their identities with makeup and masks, only referring to themselves as Nameless Ghouls. This mystery, plus their music, has led to acclaim and a few recent legal headaches.

Through lawsuits over royalties and disputes over what it means to be in a “band” of this nature, some members have been revealed and some relationships have been compromised.

“I have been in the band since I started the band,” explains the Nameless Ghoul which we spoke with. “I started writing songs for it in 2006.

“There has been about 10 to 15 people now going in and out of the band so, there’s been a lot of rotation.

“It’s never really been a band in the classic sense in that you have someone who plays his or hers instrument and that she or he is the only person in the world that can make it sound like that. People, have a tendency to want to feel that they’re very important for something. If it’s not crucial that they’re there, there will also be a little bit of a friction there.”

That distinction of what makes a person a member of the band Ghost has been an ongoing conversation and source of legal scrutiny. As it sorts itself out behind the scenes, Ghost remains busy. A new album is in the works, set to start production after they end their own headlining tour this summer.

“I know very clearly what the new record will be about,” says the Nameless Ghoul. “The new record that we’re gonna start recording now in August is something that I’ve been working on for three or four years.”

You can see Ghost this Sunday at Wells Fargo Center with Iron Maiden, or catch them later this summer on July 20 at The Fillmore in Philadelphia.

To hear much more from our talk with the Nameless Ghoul of Ghost, check out the full interview below.