A band of adventurers must traverse a series of interdimensional gateways known as the Pools of Darkness to hunt down Bane's most formidable servants scattered across distant realms. Each lieutenant—a primordial dragon, demonic entities of tremendous power, and a towering Balor warrior—guards mystical artifacts essential to reaching Bane's own domain. The journey demands clearing multiple strongholds and temples while managing the dangerous side effect of portal travel, which threatens to obliterate valuable equipment unless carefully stored away. Along the path, the party encounters legendary figures like the wizard Elminster, who facilitates their dimensional crossings, and can undertake various optional campaigns to gather strength for the trials ahead. The final confrontation pits the heroes against Gothmenes, Bane's mightiest lieutenant, in a climactic battle that will reshape the fate of the realm itself.