The story begins with our protagonist waking up inside a nautiloid, a dimension-crossing illithid flying ship. They are implanted with an illithid tadpole, parasites that enthral and transform people into creatures known as mind flayers; however, before the transformation is complete, the ship comes under attack from githyanki warriors and their red dragons. The protagonist is freed during the fighting and steers the damaged ship back to Faerûn, where it crashes. As the protagonist searches for a way to remove their parasite, they encounter other survivors of the wreck, all likewise implanted with tadpoles: the githyanki fighter Lae'zel, the Sharran cleric Shadowheart, the high elf vampire Astarion, the human wizard Gale, the human warlock Wyll, and the tiefling barbarian Karlach. Meanwhile a deadly cult which follows a mysterious entity called the Absoulte has started to gain traction and spread across Faerûn, and coincidentally seems to be the source of the recent rise in tadpole infections.
