B1, Journey to Hell is an adventure for both the OSRIC (or other favorite old school version) and the Altus Adventum 2nd edition role-playing games. Versions for both systems are included. It is based off of Dante's Inferno, and takes the heroes into Hell itself in a bid to save the king. This adventure is designed for characters level 18-20 (OSRIC version) or Legends (Altus version).
While not being directly linked to the A1-A4 series of $1 adventures from Sacrosanct Games, there are a few references to those modules. While none of those are required to play the game, having them would put a lot of things into better context if you had.