On December 18, 1998, Agent Thomas Rogan receives a short, distressing phone call from his fiancée, Sophie Richards, at the Curien Mansion, the home and laboratory of Dr. Roy Curien. Rogan and his partner, Agent G, arrive to find the estate overrun by hellish creations. A mortally wounded man gives them a small field journal with information on Curien’s deadly creations and their weak points, which is used whenever the player faces a boss.

Curien is described as a biochemist and geneticist supported by the DBR Corporation and its team of scientists. His obsession with the nature of life and death drives him into madness, and his experiments take a gruesome turn. As his subjects are released into the world, Rogan and G enter the mansion to find Sophie and bring Curien to justice.

Along the way, they face enemies including The Chariot, The Hanged Man, The Hermit, and The Magician. The Magician kills Curien, then forces Rogan and G into one final battle before exploding. After leaving the mansion, alternate endings may show Sophie alive or reveal that she has become one of the undead, depending on the player’s final score and number of continues used.