From a Rolling Stone online article:
The album was rumored to be originally titled Look, but the title was changed to In Through the Out Door as a nod to the band overcoming their struggles. (“That’s the hardest way to get back in,” Page said). Hipgnosis — the English design company co-owned by Aubrey Powell and Storm Thorgerson — designed six different album sleeves, each depicting sepia-toned scenes in a New Orleans–inspired bar. Copies were famously packaged in brown paper bags, concealing which cover was purchased. Even with this odd gimmick, the record sold an astounding 2 million copies in the first 10 days of its release. With record sales at a dangerous low, the album’s success helped revive an ailing industry.
Instead of embarking on a tour, the band decided to return to the stage with two outdoor shows at England’s Knebworth Festival on August 4th and 11th, 1979 — their first time playing on U.K. soil in four years. In the video above, they tear through “In the Evening” with Bonham taking the lead, pounding the drums during an intense strobe-light display. “So don’t you let her get under your skin,” Plant sings. “It’s only bad luck and trouble/From the day that you begin.”
To read more click on the following link: https://www.rollingstone.com/music/music-news/led-zeppelin-in-through-out-door-knebworth-1979-866992/