A live recording from a single legendary performance by Thresh & The Undertow, captured on February 14th, 2204, at a relocated underground venue in the Circuit district known that night only as 'the Furnace Room' — its actual location was a decommissioned water treatment plant in Tier 2's industrial western corridor. The show was unannounced until six hours before doors, distributed via encrypted mesh invitation to fewer than 300 people. The recording was made by audience member Saoirse Adeyemi-Pryce on a modified analog tape rig, with secondary digital capture by three others in attendance. The resulting composite recording, assembled over four months, captures the full four-hour performance with only minor gaps.

Thresh & The Undertow performed their entire catalog that night alongside forty minutes of material never recorded in studio. Standout moments include an extended version of 'Corridor Ruin' that stretches to twenty-two minutes, incorporating live improvisation where lead vocalist Caius Ndlovu-Ferreira negotiates the melody with the crowd in real time — at several points the audience is singing harmonics back to the band, and the recording captures this as a single organism breathing. 'Saltline' — a previously unreleased track about the slow chemical contamination of Tier 1's water supply — was performed once that night and never again; Ndlovu-Ferreira has never explained why. The album closes with a cover of a pre-Meridian folk song, its origin debated by scholars, performed a cappella by the full band and a significant portion of the crowd.