Living in Soho in the West End of London, Jekyll is a kind and respected English doctor struggling with repressed evil urges.

As time goes by, Hyde grows in power and eventually manifests whenever Henry Jekyll shows signs of physical or moral weakness, no longer needing the potion to transform.

However, it is Hyde's violent activities that seem to give him the most thrills, driving him to attack and murder Sir Danvers Carew without apparent reason, making him a hunted outlaw throughout England.

The first reveals that Lanyon's deterioration and eventual death resulted from seeing Hyde drinking a serum or potion and subsequently turning into Jekyll.

But as Jekyll used Hyde to act out his desires more and more, he effectively became a sociopath — evil, violent, self-indulgent, and utterly uncaring to anyone but himself.

Meanwhile, Jekyll returned to his home only to find himself ever more helpless and trapped as the transformations increased in frequency and necessitated even larger doses of potion in order to reverse them.

After sending Poole to one chemist after another to purchase the salt that was running low only to find it would not work, he assumed that subsequent supplies all lacked the essential ingredient that made the potion successful for his experiments.

It premiered on May 24, 1990, at the Alley Theatre in Houston, Texas, with Chuck Wagner playing the title role(s) and Linda Eder as Lucy Harris.

The stage version includes several character changes: Jekyll believes the evil in man is the reason for his father's mental deficiencies and is the driving force of his work; he is also engaged to Sir Danvers' daughter, Emma, while her former lover, Simon Stride, is still longing for her affections.

Hyde also murders seven people in the musical: each member of the Board of Governors at the hospital where Jekyll is employed and rejected his work, along with Lucy and Stride.

Other notable actors to play the role(s) include: Jack Wagner, Anthony Warlow, Sebastian Bach, David Hasselhoff, Rob Evan, and Constantine Maroulis in the 2013 revival.