midnight
* * * * * The night wore on and Bentley 's stride became faster . Now and again he peered into the girl 's room . She was sleeping the sleep of utter exhaustion and he did not waken her . Bentley felt it was near midnight when Barter returned , his return heralded by a strange commotion in the clearing , and the frightful drumming of the great apes -- or at least _ one _ great ape . Bentley shuddered as the animal behind the locked door answered the drumming challenge with a drumming thunder of his own . Barter came in , and Bentley accosted him at once . `` See here , Barter , '' he began .