four o'clock
`` That is not quite clear , '' said Vivi frowning . `` This looks like it -- but again this line -- the cold calculating streak in your nature -- '' At this moment , from down the beach , came a shrill whistle imitative of the whip-poor-will , insistent , querulous and repeated . Vivi dropped his hand and glanced hastily at her watch . `` Good heavens , it 's four o'clock ! '' `` All right , I 'm on . Who 's the little bird ? '' said Skippy , who had not heard himself described as the acme of suspicion for nothing .