Henry Jekyll is a troubled man. His wife died of pneumonia. He wants his sister-in-law, but her father forbids any contact. And his experiments into the dual nature of man have yielded a personality-splitting drug that he has tested on himself, changing him into an uninhibited brute who seeks violent and undignified pleasures. Jekyll quickly becomes addicted to the sordid freedom induced by the drug. He can commit the most enjoyably revolting deeds, then return to his laboratory and use an antidote to change back to his original form, so that his lofty persona remains untarnished.

When a group of people from different walks of life converge in a Hungarian castle situated in Budapest which has been sealed for 500 years, they bring with them a werewolf which slowly begins to cut their numbers down.

When his experiments into a powerful new anesthetic go hideously awry, respected physician Dr. Jekyll transforms into the hideous Jack Hyde. As his wife Elisabeth passes her time in charitable work, rehabilitating the district's fallen women, Hyde is drawn into an escalating cycle of lust and murder that seems to know no bounds.

Major Charles Forsythe is a Vietnam veteran U.S. Army officer stationed near Rome. He is a brutal, if effective, commander who was "fragged" by his own men in Vietnam. When he is denied promotion because of the number of men injured during his training exercises, he takes out his anger by beating his pregnant wife Sarah. She miscarries. On her release from the hospital, Sarah is determined to get back into shape and begins running. She meets Alan Morani a former Olympic runner who is a paraplegic as the result of a car accident. Morani offers to coach Sarah to run in the Rome marathon, a race which her husband has won two years in a row. Sarah realizes that winning the race is the best way to avenge the death of her baby and destroy her husband's ego.

A black Union Army deserter and his crippled American Indian hostage form a strained partnership in the interests of surviving the advancing threats of a racist bounty hunter and neighboring bandits.