about midnight
And I gathered that Mr. Burns , the other detective , had followed a similar car for miles at dawn , only to find it was a touring car on an endurance run . `` He left here about ten minutes after eight , '' Mr. Jamieson said . `` He went alone , and at eight twenty he stopped at Doctor Walker 's . I went to the doctor 's about midnight , but he had been called out on a case , and had not come back at four o'clock . From the doctor 's it seems Mr. Innes walked across the lawn to the cottage Mrs. Armstrong and her daughter have taken . Mrs. Armstrong had retired , and he said perhaps a dozen words to Miss Louise . She will not say what they were , but the girl evidently suspects what has occurred .