From publisher blurb:
Into the Gates of Hell now features gate connections to three other Hanan Pacha adventures: Lair of the Demon Princess; Beyond the Black Door and The Inn of Limbus. Also included is the new work: Gate Connections, which has a graphic that shows all of the above gate connections.
Into the Gates of Hell: take your adventurers on a quest to find the keys to nine gates that intersect with the infernal regions. Battle devils and a host of other monsters that lurk in this place of darkness and evil. These magical gates may or may not be open. Complicating matters is the fact that a dangerous group of mercenaries have already infiltrated the dungeon!
This module is written for a group of adventurers of 7th to 12th level. PCs of all classes need magical weapons sufficient to battle extra-planar creatures effectively.