Another Villain Who… (spoilers)
…starts out as cunning, then gets stupid for plot purposes.
That ending was laughably bad, and we didn’t even get a true ending. For all we know, Jeff died, Adam survived, and Donna was arrested for murder and attempted murder.
I’m just going to headcanon that as my ending because Donna was annoying anyway.
Also, what was with giving Adam a tragic backstory and the doing nothing with it? If Donna has thrown that in his face, at least that would have explained his sudden irrationality behavior.