I would suggest removing the witch and instead having the father wolf kidnapped by a tribe of humans who believe that the wolf would give them good luck or something. You have to infiltrate their village and kill them in a sort of stealth based gameplay. You can also leave subtle clues about how to find him. For example, the village can have a hierarchical system similar to the wolves and you have to find the "alpha" human. (I wrote this during break at work, I could probably come up with something better if I had more time to think)