After cutting their teeth playing around London, saxophonist Joe Henwood and drummer Tash Keary linked up to jam during pandemic lockdowns. As gigs returned, O. became an official duo, taking up residence at Windmill Brixton—the South London venue now famous as the incubator for acts like Shame, Squid, black midi, and Black Country, New Road. They caught the ear of Dan Carey, the prolific producer linked to almost everyone in the current UK post-punk boom, and recorded the charmingly titled WeirdOs for his Speedy Wunderground label. But if “post-punk” quickly became a reductive umbrella for the host of adventurous bands percolating in South London, O. represent a particularly arcane new subplot.

While Henwood and Keary came up in London’s equally vibrant and of-the-moment jazz scene, O. are not jazz. They aren’t any one thing, but a collision of Henwood and Keary’s disparate interests, name-checking everything from dub to Deftones, noise to A Tribe Called Quest. The two boast jazz technicality, but perform with the viscerality of punk and metal, while favoring textures and colors more akin to bug-eyed electronic music. Their style is muscular, high intensity, and a little gonzo. Keary’s drumming is typically furious yet precise, Henwood’s baritone sax riffs heaving and monolithic. This was the energy that producer Carey sought to capture: WeirdOs was cut live to tape in two weeks, seeking to replicate the urgency of O.’s gigs.

Everything in O. is about mutation as the duo chase freeform ideas far into the ether. Much of this experimentation is achieved by Henwood’s extensive manipulation of his sax, filtered through an array of effects pedals. On penultimate standout “Sugarfish,” you can feel the bodily heft in his distorted lead, before it turns into something more closely resembling aqueous synths, only to resurface sounding almost like a guitar.

O. pull off similar tricks across WeirdOs. “Micro” sounds like a smeared electronic track, melting Keary’s jungle breakbeats and Henwood’s sax nearly beyond recognition. O.’s fascination with metal shines through in the foreboding rhythms of “Cosmo” and “Slap Juice.” On “Whammy,” Keary switches from blitzkrieg propulsion to suggestive tumbles, Henwood from the natural guttural strength of the bari to more otherworldly and sinuous lines, before the whole thing erupts again in its final act.

While hooks abound, WeirdOs also plays as one big, roiling piece. Like the live jams from which it emerged, the album has peaks and valleys, passages of unrelenting intensity followed by space-out cooldowns that offer the slightest moment to breathe. Those with jazz predilections might hear it as a violent deconstruction of the genre, while followers of London’s rock scene might perceive O. as the most eccentric wanderers to yet grace the Windmill’s stage. No matter how WeirdsOs reveals itself to you, O.’s debut is a testament to Keary and Henwood’s fearlessness and dexterity. They take the limitations of two players and two common instruments, and tell the story in a way never heard before.