Jeff Randall and Marty Hopkirk are best friends who run a detective agency. The night before Marty is to marry his fiancee Jeannie Hurst, he dies, apparently killed by a suicidal woman he was hired to protect from herself. Marty's ghost returns to earth for one night, visible only to Jeff, to try to sort out the truth about his death. He stays too long on earth, however, and is "cursed": "Ye shall not to the grave return until your chosen one be gone."
Jeff carries on with the detective agency, and Jeannie quits her job as a waitress to help Jeff. Marty shares his time between helping Jeff on cases and lessons with Wyvern, the ghost who has been assigned to help Marty adjust to being dead.
Jeannie is hired by Stuart Boyle, Jeff's old school friend, to investigate a mysterious letter he received from his long-dead father. It says to meet him at Boyle's department store. When Jeannie arrives at the abandoned department store, she finds that it has been renovated, but is now filled with deadly traps and fiendish games; Jeannie is drugged and awakes to find herself and Stuart tied to chairs. Meanwhile Jeff and Marty discover Jeannie is missing, but they bicker so much that Marty's spiritual bond with Jeff is severed and he finds himself in the despair-filled seaside town of Rhadamanthus-On-Sea. Jeff heads to Boyle's, where he finds Jeannie and Stuart, frees them and then they attempt to escape from the deadly store...