Despite being one of rock's most extravagant individuals, David Bowie could be equally invisible. The '00s made that clear.

He had left music behind after experiencing chest pains on stage in June 2004 in Germany, seemingly for good. The rest of the tour was canceled, and Bowie underwent immediate surgery after doctors found a blocked artery.

"I'm fed up with the industry – and I've been fed up for quite some time,” Bowie told New York magazine in 2006. "I'm taking a year off — no touring, no albums."

Then a year became close to 10. Bowie not only stepped away from music, he largely retreated from the public eye. Every so often, he would appear or perform at high-profile events — David Gilmour's 2006 concert at the Royal Albert Hall, for example — but for the most part, Bowie kept to himself.

Oftentimes, even in later years, he could be found hiding in plain sight. Bowie would carry a Greek newspaper to throw people off his scent. "People think: that's David Bowie, surely?" he once explained. "Then they see the Greek newspaper – no, can't be, just some Greek guy who looks like him."

Eventually, however, the music called. Bowie re-entered the studio in 2011 and began putting together a new album. He alerted as few people as possible.

Watch David Bowie's Video for 'Valentine's Day'

Longtime producer Tony Visconti was one of them. As sessions for the LP that became The Next Day continued, people asked Visconti what he was working on. He would only say a "very big project," adding that he'd been sworn to secrecy.

"That satisfied most people, but then a few people would say 'It's Bowie, isn't it?'" Visconti told The Guardian in 2013, "and I'd go, 'I can't tell you who it is. Even if you said the person's name, I can't say yes or no.' And they'd go 'It's Bowie,' and I'd go 'No, really it isn't.' I was a little uncomfortable with that, but it was the only way to do it."

Regular guitarist Earl Slick found out that Bowie was back in the studio in a suitable rock 'n' roll fashion: by getting involved in a blazing car accident.

"I did a gig in New Jersey and I stayed with a friend. We went for a ride in his Cobra, and the car caught on fire," Slick told MusicRadar in 2013. "One of the guys from the newspaper that came to cover the thing recognized me, so there was some press about it."

Bowie saw the coverage and sent Slick an email asking if he was alright, followed by another asking if Slick was free to join the session. "And then, over the period of the next 24 hours, we put together the schedule for me to come into the studio," Slick said. "So I have my buddy's Shelby Cobra blowing up to thank for that one. Sucks for him, but that’s how it happened.”

Listen to David Bowie's 'If You Can See Me'

Neither Visconti nor Slick was all that surprised that Bowie decided to resume recording. "One thing I did know is that once you’re an artist, you’re an artist until the day you die," Slick told Rolling Stone at the time. "The urge is always going to be there. I was never sold on the idea that he was done. Never."

Recorded in New York City between May 2011 and October 2012, The Next Day tended to harken back to Bowie's so-called Berlin Trilogy with its grittier art-rock edge, but elements from a variety of his past LPs were also present – including the free experimentation of 1997's Earthling ("If You Can See Me") or the glam-rock touches of Ziggy Stardust ("Dancing Out in Space.")

Lyrically, however, The Next Day was one of Bowie's darkest offerings to date, with songs about his former haunts ("Where Are We Now?") and school shootings ("Valentine's Day"). According to Visconti, Bowie had been absorbing books on medieval English history and contemporary Russian history, both of which permeated the album's songs. The Jonathan Bambrook-designed cover also nodded to the past, featuring a modified version of 1977's "Heroes" with the title covered.

The secret became harder to keep, as work continued. Slick was spotted by a cameraman outside the studio in October 2011, leading to more rumors that Bowie was up to something. At the same time, their strict confidentiality was becoming a burden, Visconti admitted.

"We had to talk about it about it as a group, share our experience of the insanity, the frustration. And David would just sit there smiling," he told The Guardian. "The fun we were having in the studio overshadowed all the neuroses, but there definitely were neuroses."

Watch David Bowie's Video for 'Where Are We Now?'

The Next Day was completed and readied for release on March 8, 2013, but Bowie did not have a promotional campaign plan. Rob Stringer, then-president of Sony Music Group, came by the studio to hear some tracks and Bowie said he didn't want one. Instead, he would simply release "Where Are We Now" as the album's first single without an earlier announcement on Jan. 8 – Bowie's 66th birthday.

He clearly understood how bleak the songs could be. Bowie met with a writer from The Rumpus a few months later to make his first public statements and was asked for a "workflow diagram" of the album. Bowie selected 42 words, many of them shrouded in darkness:

"Effigies, indulgences, anarchist, violence, chthonic, intimidation, vampyric, pantheon, succubus, hostage, transference, identity, mauer, interface, flitting, isolation, revenge, osmosis, crusade, tyrant, domination, indifference, miasma, pressgang, displaced, flight, resettlement, funereal, glide, trace, balkan, burial, reverse, manipulate, origin, text, traitor, urban, comeuppance, tragic, nerve, mystification."

Despite all of that, the results delighted fans. The Next Day debuted at No. 1 on the U.K. chart, becoming Bowie's ninth chart-topping LP – and the first since 1993's Black Tie White Noise. The album went to No. 2 in the U.S. and is generally regarded as one the strongest releases of his career.

After such a lengthy hiatus, new music from Bowie came as a comfort to many – including those who had long kept it under wraps. "So relieved to talk about the new [David Bowie] album after two years of silence on the subject," Visconti wrote on Twitter as the first single was released, adding that it was "like a dam broke."

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