Durante got himself nicked by the Abbey boys, which means that they've got his office key, and it means he might have told them how to open the Jindosh Lock.
I need you to find a way to open Durante's door, and no, burning the building to the ground in not an option.
I also want you to start dropping off food for old Stilton until we find someone to replace Durante. Once you manage to get his office open, you'll find all the details inside. Be very careful when you go into Stilton's Manor. If the Overseers do have the code to the Jindosh Lock, they might want to have a peek inside too.