four
o'clock
With that she left him , and she did not look back as she and Peggy Blackton went into the house . But as they drove away they saw two faces at the window that overlooked the townward road , and two hands were waving good-bye . Both could not be Peggy Blackton 's hands . `` Joanne and I are going for a walk this afternoon , Blackton , '' said Aldous , `` and I just want to tell you not to worry if we 're not back by four o'clock . Do n't wait for us . We may be watching the blow-up from the top of some mountain . '' Blackton chuckled .