What is the plot of "The Strange Case of Dr. Jekyll and Mr. Hyde"?

At the
start, readers learn that a Mr. Hyde attacked a young girl.  A respected doctor has written a
will giving all his possession to this violent man, which puzzles the doctor's friends.  People
haven't seen much of Dr. Jekyll lately.  Utterson, a friend of Jekyll, looks into Mr. Hyde and
finds that he hangs out at a laboratory at Jekyll's home.  Utterson is amazed at how ugly Hyde
is. He questions Jekyll, who tells him not to worry about...