four o'clock
No one at all except myself will see you go into the vault . I can manage the operation alone . A little chloroform will quieten you for a time . The vault once closed will not be opened during my lifetime , unless at four o'clock to-morrow night I hear you knocking on the door . Of course , inquiries will be made , but they will be futile . People often simply disappear . You will simply disappear . '