So it sent me to trevas watch to get these plans, I cleared out the place completely, and I searched literally EVERYTHING and found no plans at all. There was also no quest marker the whole time. Not until I got into trevas watch, and the mark I saw was off the map entirely (in the void outside the dungeon graphics). There was nothing there of course. I also could never display the quest on my map, it simply didnt ever show up on the world map.

Also spawning the silver hand strategem with the console doesnt work either. Nothing abouyt the quest updates. So i figured I would go back the companion hall. Everyone gives me work, as if that quest I have doesnt exist and I was never given it. But its still in my journal.

I ran into the same problem. I thought it might have been because I completed the "main" part of the Companions storyline before I did this quest (trying not to spoil anything here).

Either way, hope there's a fix.

Same issue here too, got sent to Faldar's Tooth to get the plans, cleared the place, no plans. The quest doesn't show up on my map when I mark it either.

Dito except says its at Fellhammer ,all my companions are also stuck just after the attack on Jorvaskar ,so I cant marry the huntress to get free archery lessons, hope they sort it. Otherwise this is my favorite game.

I found this site that sorted it for me, check out the bug section,http://elderscrolls.wikia.com/wiki/Blood%27s_Honor, hope it helps.