White Plume Mountain is set in the World of Greyhawk, a campaign setting for Dungeons & Dragons. The earliest known inhabitant of the volcano known as White Plume Mountain is the druid Aegwareth. Aegwareth is later slain by the evil wizard Keraptis, who took over the mountain with his gnomish servitors. The premise of White Plume Mountain is that thirteen hundred years ago, Keraptis descended into the volcanic mountain with a company of gnomes, and disappeared. The adventure is a dungeon crawl, and hinges on Keraptis' theft of three powerful magical weapons: a trident named Wave, a war hammer named Whelm, and a sword named Blackrazor, all of which have their own intelligence and were first introduced in this adventure. The weapons' former owners each received a copy of a taunting poem, instructing them that the weapons are in White Plume Mountain. The characters' goal is to enter into the Wizard's Mouth, a fissure in the side of the active volcano, to rescue the magical weapons from Keraptis' lair.
The adventure's 16 pages are divided into 27 encounters. The player's characters begin in a cave at the base of White Plume Mountain. In the first numbered encounter, the characters find a spiral staircase in the cave which leads to a "mangy, bedraggled" gynosphinx. Encounter seven involves a large cave with a floor of boiling mud. Circular wooden platforms are suspended from the ceiling, and the characters must jump from platform to platform while dodging geysers of hot mud. In the eighth encounter, the characters confront a vampire who is guarding the magical war hammer Whelm in a room of permanent darkness.