So I spoke to Tarquin the first time normally. He gave me the 'All in the Family' quest. I went down into the crypt and did the first part of it, getting the first half of the weapon and moving the quest log along to "We found a strange object in the crypt. Maybe this is the artifact which Tarquin seeks?".
So along to the 'usual' bug. When I exit the crypt, Tarquin is not where he was, nor is there a 'Tarquin's Whereabouts' map marker. I can't find him anywhere, so I resorted to looking it up to see what others did in this circumstance. Unfortunately, their fix isn't working either. He's not back on the Lady Vengeance. He's not near the lifeboat. He's not.. anywhere. I'd really like to finish the quest (obviously). Is there any way of proceeding from here? I've searched the entire graveyard, and the number of different ways people have found to work around this problem don't seem to be helping in my case.
Thanks very much in advance.