The crew catch a virus that de-evolves them.
Everyone turns into a monster? Really? That is not how evolution, or even viruses work. Not even close. I’m normally pretty liberal with my definition of science fiction, but this isn’t anywhere near what’s needed.
So there’s bad acting as everyone starts to de-evolve, some really terrible stuff as Picard and Data return to the enterprise, and then a terrible chase sequence to finish things off.
One of the worst things Trek has ever done.
317 down, 420 to go.