Trial of the Beast Defense Help

[Booke]

My group recently dived right into this book real easy when I told them about how the beast was on trial and was going to be put to the fire. Eventually, they got the idea of disguising one of them into the Beast himself and running amok the town proving that it couldn't have been the beast since there's another one out there. I know by RAW, they'll really need Polymorph Any Object to really do this, but they are really stuck to the idea of doing this and I can't really talk them out of it.

I have no idea how to respond to this, either positively or negatively. I know the people should know there's only one known Beast out there, so I think it shouldn't effect the trial at all, but I just don't want to smack my players in the face for thinking outside the box. Any ideas anyone?

[Toadkiller Dog]

Disguise is subject to perception checks. Unless they've been investing heavily in Disguise, odds are, someone will figure it out. Yes, maybe they'll scare some townfolk, but once the guard arrives on the scene, all it takes is one good perception roll to figure out someone is just disguising themselves.

Not to mention that they have a -2 penalty on disguise because they're trying to disguise themselves as another race and then another -10 for trying to disguise themselves as a large creature. And because they're trying to disguise themselves as a particular individual they have an additional penalty of -4.

Assuming max ranks in Disguise, class skill and decent charisma (16) and a Disguise Kit, that PC could have a +12 on Disguise, for the total modifier of -4.

With their plan doomed to fail, I'd just arrest the PC that tries to pull off. That way, he'll be close to the Beast (perhaps gain its trust and some more vital information, but unable to convey it to other PCs) while the rest of the party now is a man short but they still have to go with the trial.