You are probably referrng to the afternoon when Mr. Enfield and Mr. Utterson were out walking and saw Henry Jekyll at the window.  In the middle of the conversation, Jekyll's face suddenly darkened and he quickly closed the window without barely saying good-bye to his friends.  Both Enfield and Utterson walk away in silence, each keeping his thoughts to himself about the strange occurrance. Neither probably wanted to speculate on the possible reasons for Jekyll's behavior, which would have been considered rude, especially in his position in Victorian Society.  Only Mr. Utterson ever learns the truth about Edward Hyde through Dr. Lanyon's letter and through Henry Jekyll's written confession.  The novella ends with the confession, so the reader can only guess Utterson's reaction to the revelation about Mr. Hyde.