Larian Studios Forums Beyond Divinity (English) Help/Tips/Tricks Cannot find Act I, BF3 key

I have completed almost all of Act I, even seen Samuel get summoned away but I still have been unable to find the key for the third battlefield of Act I.

I also tried numerous searches of the forums for keywords like key, BF3, Act I, etc. but have yet to find a thread that specifically mentions where it can be found.

Is there some part of the last level of Act I that I haven't completed that contains this last key?

Thanks,
rpger