While investigating a diamond heist, disgruntled cop Harper falls for Holly, the top suspect's main squeeze. When she convinces him to kill her boyfriend and make off with her and the loot, they start down a treacherous path full of dark surprises.

Down-and-out artist Joe Manning wakes up from a night of drunken revelry in a jail cell, where he's being held on suspicion for the murder of a nightclub singer.

In 19th century England, a noted brain surgeon rescues a former student from being hanged on a false conviction for murder, and spirits him away to an ancient, repurposed abbey far in the countryside. There, he connives his pupil into assisting him in mapping the functions of the various parts of the human brain, using living subjects who are under a terrible animation-suspending drug called "black sleep". Subsequently, the student, along with the daughter of one of the subjects, discover that most of these subjects have survived but are being kept in a dungeon-like cellar, in various stages of physical and mental derangement...