midnight
She agreed to act as sentinel during the night , to keep a vigilant lookout from the treetop , and in case of approaching danger instantly to awaken Ned and the giant . Gradually the great castle grew quiet , until nothing was stirring , `` not even a mouse . '' At times the night wind rustled the leaves in the tree where the little bluebird sentinel sat winking and blinking , and the big yellow moon glistened fantastically on the big toe of the giant . Toward midnight a faint sound in the distance , like the beat of horses ' hoofs , startled the bluebird . Hastily flying toward the castle entrance she gazed out upon the roadway that wound up from the valley below . At some distance she made out dimly the figures of a number of horsemen . Returning swiftly to the castle , she tweaked the giant 's big toe .