Sir Walter Scott's classic story of the chivalrous Ivanhoe who joins with Robin of Locksley in the fight against Prince John and for the return of King Richard the Lionheart.

In the 13th century, Walter of Gurnie, a disinherited Saxon youth, is forced to flee England. With his friend, Tristram, he falls in with the army of the fierce but avuncular General Bayan, and journeys all the way to China, where both men become involved in intrigues in the court of Kublai Khan.

In 1840s London, Dr. Thomas Bolton [Boris Karloff] dares to dream the unthinkable: experimenting with anesthesia gases to make surgery pain-free. While doing so, his demonstration before a panel of his peers ends in a horrific mishap with his patient awakening under the knife; he is forced to leave his position in disgrace. To complicate matters, he becomes addicted to his own chemical experiments and gets involved with a criminal gang led by Black Ben [Francis de Wolff], and a ruthless killer Resurrection Joe [Christopher Lee]. Unfortunately, this shady partnership leads Dr. Bolton to further ruin, culminating in his unwitting participation in murder — for which he becomes the first victim of a blackmail scheme.

After fierce Roman commander Marcus Vinicius becomes infatuated with beautiful Christian hostage Lygia, he begins to question the tyrannical leadership of the despotic emperor Nero.