Dr Jekyll and Mr Hyde

Mr Utterson is worried about his friend, doctor Henry Jekyll, and in particular about Jekyll's friendship with the sinister Mr Hyde. Why does the doctor spend his days alone in his private study?
Why does he look so tired and ill? Stevenson's classic tale explores the conflict between good and evil in Man's nature, the hypocrisy of Victorian society and the horrors of drug abuse in a thriller that has fascinated readers for decades.