midnight
Where 's your character , Libbie ? '' Libbie scowled , but departed , grumbling that she did n't see why she could n't stay up and watch Norma walk down in the cellar . `` Mine is the most spooky , '' said Betty , when the door had closed behind Libbie . `` Listen -- I 'm to climb the water tower at midnight and leave this card there to show I have complied . '' She held out a little plain white card in a green envelope . `` Hark ! was that somebody at the door ? ''