Collected here is an unreleased demo, their "Never Healed" EP (originally released as a flexi on Earache Records), their later "Thanks" EP and a couple of random tracks that never saw the light of day. These releases form only the early part of the bands collective career, but due mainly to the inclusion of "Never Healed", out of the three discog LP's that occurred, this one would arguably be the best. No frills, relentless, fast hardcore from a scene and time that spawned other greats like Ripcord and Napalm Death.
Heresy are often credited as playing an important roll in the early stages of the development of grindcore and I suppose I would agree. One could argue that obviously Napalm Death were the real purveyors of the genre originally though. For the better part, the vast majority of Heresy's later catalogue suffered quite a bit due to factors like bad recording qualities and just plain shitty songs, but this early stuff was fantastic.