In the short amount of time Black Midi have been a band, they have stirred up a frenzy of hype in their native UK primarily on the strength of their live show. Up until this year, after all, they had barely any music available online, and they kept their debut album Schlagenheim — which ranked in the top 10 on our list of the best albums of the year so far — shrouded in mystery as long as possible. When a band like that arrives, there’ll always be those who are dubious, who think there’s just some shtick or industry fervor behind the whole thing. But, chances are, if you’ve seen Black Midi live before, you know the hype is justified. They proved that over and over at their triumphant SXSW earlier this year, and they really proved it last night in Chicago.

Yesterday was a tricky day at Pitchfork Music Festival. After the threat of storms looming over the entire weekend seemed to disappear, it looked as if Saturday would be a clear day. Then, as Parquet Courts were getting lost in the groove of “Wide Awake,” an evacuation announcement went out over the speakers. The ensuing storm passed quickly enough, but it meant several of the day’s artists weren’t able to play, and the grounds of Union Park were reduced to swamplike textures.

After all that trouble, there were also after shows to enjoy. Given Pitchfork Fest’s early curfew, a lot of these shows function more like a normal gig on any given night in a city, with reasonable set times in ordinary Chicago venues. There were a couple last night — including a Snail Mail show at Thalia Hall where Soccer Mommy joined Lindsey Jordan on a Goo Goo Dolls cover — and one from Black Midi at the very appropriately-titled venue the Hideout. Tucked away on a nondescript corner, it felt like a fitting scenario in which to see Black Midi — a pilgrimage to find this strange foreign band conjuring up all kinds of noise in a small room.

When the Black Midi buzz first arrived Stateside, it was still driven by their live show, just as those initial whispers in London were. Schlagenheim already delivered in a different way, proving not only were these guys exhilarating onstage, but they could write music that was hypnotic and shape-shifting and often quite addicting. Road-tested and jammed out over time, the material on Schlagenheim has a loose, unspooling, exploratory quality to it, but it’s also been refined, cut down, focused in on the strongest hooks or the most alluring guitar breaks. It’s one thing for a rising band to have a fervor to their live shows; it’s another for them to arrive with a debut album as assured and exciting as Schlagenheim, one that stands as a strong achievement alongside the pre-existing onstage reputation.

All of that being said: You really need to see Black Midi live to get the full impact and the full story. That was clear before any of these songs were released, during those spring shows in America. But after the album’s been out in the world now, after we’ve all had some time to sit with it and familiarize ourselves with all its twists and turns, it appears Black Midi have already begun to continue evolving onstage.

At the Hideout, the band reminded us that they are musicians first, songwriters second — they play, their four dispositions colliding in all sorts of combustible forms, and then these songs are wrung out of the fury they kick up together. You might even walk away slightly suspicious that the quartet are already a little sick of their debut, given these songs have been around for a while and their sly allusions to the idea that Black Midi will never sound the same from era to era. So now, with some removal from Schlagenheim’s release, Black Midi are playing sets that are even more fluid and adventurous, accentuating certain aspects of the album’s best cuts and imploding others.

Over the course of about 50 minutes, the band ran through fewer than 10 songs, which played out more like one elaborate extended piece of music. The borders of these compositions became permeable, tracks spreading out beyond the confines of their recorded versions and each one connected by long jams or little transitional passages that hinted at the next song as the preceding one was still dissipating. As usual, they are not a talkative bunch. It was just one long wave of roiling sound, Morgan Simpson’s dexterous drumming providing an engine for the rest of them to bend their instruments beyond recognition.

The heaviness of it all. That was the big takeaway last night. Black Midi were always caustic, and Schlagenheim was a better reflection of their live sound than many bands’ LPs. But the intensity was on a whole different level at the Hideout. There are plenty of riffs on the album that get you right in the ribcage and yank you along. And they really unleash those now. The swaggering maelstrom of “953” almost sounded like a metal band, the riffs became so physical, so overwhelming. The songs that were already ragers, like “Years Ago” or “Near DT,MI,” were pushed deeper into the red. Even comparatively mellow material like “Speedway” had Rage Against The Machine riffs thrown on top of its burbling outro. (Which was kind of amusing, given they’d wryly marveled at a security guard at SXSW comparing them to RATM.)

It all came to a close with the song that started it all. “BmBmBm” is a song built for volcanic concert climaxes. And Black Midi know what they have on their hands there. The set had already cycled through plenty of dramatic and cathartic arcs. But by the time that distinctive, foreboding “you know shit’s about to go down” riff started, they were setting up the biggest payoff of the night. There had been quite a little storm in Chicago that afternoon. This one felt as if it reverberated louder, and farther.

The extreme heaviness, the way the band was pulling their songs in and out of focus, it was all at play during “BmBmBm” — they would test its taut rhythms and the unsettling nature of that voice-through-a-guitar business, threatening to let it all break down. So, then, when that final lurching riff erupted, it was like all the air in the room was for a second sucked onto the stage and then exploded back out across the crowd. It felt, for a moment, that it wasn’t just the songs over which Black Midi had some alchemical control, but every element in the room itself. In those final moments, you could feel like what we’d actually witnessed that night was a band rearranging matter to their pleasing, deconstructing old ideas and structures and making our very surroundings feel new again.