For one thing, I think it might be better if it wasn't just Sorn and Gurth - what if we somehow brought in Thornden etc who are going after Sorn?
I'm trying to think of how they might be in trouble other than battle-wise; Sorn doesn't exactly have many minions that are going to fight for him...
Hm - what if Osfrid managed to outsmart the four going after him, lock them in a room somewhere? That's four men MIA right there.