about ten o'clock
`` Be very wary , '' warned Dr. Cairn . `` Remember that if you died mysteriously to-morrow , Ferrara would be legally immune . We must wait , and watch . Can you return here to-night , at about ten o'clock ? '' `` I think I can manage to do so -- yes . '' `` I shall expect you . Have you brought up to date your record of those events which we know of , together with my notes and explanations ? ''