ten o'clock exactly
`` On what day are those others coming ? '' `` Wednesday -- Tuesday perhaps -- '' Beautrelet seemed to be making an inward calculation and then declared : `` Monsieur le Juge d'Instruction , this is Saturday . I have to be back at school on Monday evening . Well , if you will have the goodness to be here at ten o'clock exactly on Monday morning , I will try to give you the key to the riddle . '' `` Really , M. Beautrelet -- do you think so ? Are you sure ? '' `` I hope so , at any rate . ''