When Nirvana went into the studio to record their third — and ultimately final — studio album, In Utero, the band was aiming for a major departure from their first two albums. Instead, they landed a giant hit with an album that melded the sonic pieces of those previous two records.

Back in 1989, when they released their debut album, Bleach, on Sub Pop, the musical mainstream simply wasn't ready for the swirling guitars, massive chunks of distortion, hard-hitting drums and screamed-out slacker-pop songs penned by frontman Kurt Cobain. Sure, Jane’s Addiction, gatekeepers of what would later be called the Alternative Nation had put out their seminal Nothing’s Shocking a year earlier in 1988, but the seeds of the revolution were yet to be sown.

Just two years later, Nirvana’s follow-up, Nevermind, simultaneously took clippers to hair metal and a razor to the neck of adult contemporary. Their arrival was arguably the biggest rock 'n' roll moment since the Beatles debuted on The Ed Sullivan Show — an appearance Nirvana would later mock in its "In Bloom" video — or when Bob Dylan went electric at the 1965 Newport Folk Festival.

The grunge pandemic swept over the world with lightning speed, spawning imitators aplenty and simultaneously coronating Nirvana kings of the era. The trio's overnight success begged the question: Would a follow-up be anywhere near as massive? On Sept. 13 in the U.K. and a day later in the U.S., Nirvana answered that question with In Utero.

The first notable aspect of the album is its producer. Given the success of Nevermind, it would’ve made sense for Nirvana to once again enlist Butch Vig. But Cobain, Krist Novoselic and Dave Grohl were leaders, not followers, and they went less obvious (and less commercial) by tapping Steve Albini. A former member of noise bands Big Black and Rapeman, Albini had manned the boards on the Pixies' 1988 debut Surfer Rosa, and as Cobain and the gang paradoxically looked to widen their sound and broaden their scope by scaling things back, Albini must have seemed the man for the job.

NIrvana were also looking for a way out of the pigeonholes Mudhoney's Mark Arm and Jane's leader Perry Farrell had accidentally created by coining terms like grunge and the Alternative Nation. In Utero, like Bleach, was to be something the world wasn't ready to hear. Except this time, the world was ready, and even if the group had released a single distorted drone paired with a Hare Krishna chant, it probably would have sold a million copies.

Strangely enough, In Utero wasn't particularly groundbreaking in terms of sound. Louder? Yes. But if Nirvana were going for something truly off the charts, both in terms of sonics and sales, they only got halfway there. If you listen to Bleach and Nevermind back to back, you can hear the chrysalis of In Utero's sonic attack. It’s as if the band and Albini had ripped both previous albums to shreds and pieced them back together into one Frankenstein monster, taking the least accessible aspects of the first album and wedding them to the behemoth hooks Vig had done such an expert job crafting.

In Utero does differ from its precursors in several key ways, though. There are fewer effects and more raw, detuned guitars (The technique of dropping the low E down to a D would become a hallmark of the era). In Utero also features odd time signatures ("Milk It," "Radio Friendly Unit Shifter"), screaming speed-metal ("Tourette’s") and even cello ("Dumb," "All Apologies").

Cobain's deeper, darker lyrics, meanwhile, range in subject from the twisted pull of love and sexual violence ("Rape Me") to film, as "Frances Farmer Takes Her Revenge on Seattle" was partially inspired by a 1978 biography about the doomed titular actress. (Frances was also Cobain’s newborn daughter’s name.)

Also notable are the supremely listenable likes of "Heart-Shaped Box," "Rape Me" and closer "All Apologies." Cobain had a knack for writing pop songs in the ’60s garage and British Invasion style. These had simple structures (verse-chorus-verse) and sometimes a bridge, and they could be easily digested by a mass audience. The aforementioned catchy songs sold In Utero to the masses, while the noisier, artsier songs were there to represent the band’s growth, and perhaps to lure in fringe fans caught up in punk, metal and hardcore scenes.

Even as the band tried to break new ground and possibly even put off casual fans with a harder, less-straightforward album, In Utero was a major critical and financial success. It topped both the U.S. and U.K. charts, and the singles "Heart-Shaped Box" and "All Apologies" reached No. 1 on Billboard’s Alternative Songs chart.

While some might argue Nirvana’s MTV Unplugged in New York, recorded on Nov. 18, 1993, is actually the band’s farewell statement, In Utero was their final album of new material, and in that sense, it was their goodbye to the world. Interestingly, the final song, at least on the U.S. version, was "All Apologies." (The U.K. and European import featured the Pavement-like "Gallons of Rubbing Alcohol Flow Through the Strip.") Was Cobain leaving U.S. fans an audio Easter egg by sequencing that song last, or was it just a coincidence?

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