A lightning bolt strikes the vortex during a slide, damaging the timer and trapping Quinn on the astral plane. Now the Sliders are stranded on a world with 1950s technology and Quinn can not be seen by the others. He tries to get the help from the only one who can see or hear him, a girl that has a history of hearing voices.

On a world where a biological weapon wiped out most of the male population, Quinn, Rembrandt and Arturo become objects of desire and are imprisoned by the government to be breeders. As they try to escape and regroup with Wade, they find there are others out to capture them.

In 1755, MacLeod made a promise in order to save the life of a young friend. It comes back to haunt him when Kassim, the Immortal to whom he made the promise, demands that MacLeod assassinate the tyrannical dictator of a small Middle Eastern country. When his refusal gets a good man killed and puts Rachel's life in jeopardy, MacLeod is torn between doing what he believes is right and keeping his promise.

After separating from Ryan and Henry the dog, the Sliders make a rough landing that reopens Quinn's bullet wound. On this world of mysticism and superstition, a witch doctor heals Quinn and has brains on the mind when they can't pay the bill. On the run from bounty hunters, the Sliders only hope is the mysterious Sorcerer, a man who could possibly get them home.

MacLeod arrives in France, leaving a trail of hate and destruction in his wake. Methos finds him and discovers just how evil MacLeod has become when he tries to take Methos' head on holy ground. After MacLeod kills another good friend, Methos realizes that the only way to save MacLeod may be to kill him.