However, he went to the length of unbolting it, and opening and shutting it several times; this he did with the utmost precaution against making any noise. 
He went ahead and unbolted the door and opened and shut it loudly.
mnli hypothesis: He went ahead and unbolted the door and opened and shut it loudly. premise: However, he went to the length of unbolting it, and opening and shutting it several times; this he did with the utmost precaution against making any noise. 