Tasked with questioning the validity of a hoax, a tenacious physicist is forced to push the limitations of modern science, while the impostors face death row.

Agreed with Richiev.
You have your protagonist, but we're not clear at all about the inciting incident, what the actual goal is (and therefore, the action the protagonist takes to achieve this goal).
The stakes are nice and high, but it's unclear how an 'impostor' figures into it all. They're linked with the hoax, right? Maybe you just need to be clearer on the events of your story, and steer away from anything too general sounding.

I can't quite tell if I like this idea or not.

The phrase, "questioning validity of a hoax" seems a bit awkward.

The phrase, "Push the limitations of modern science" tells us very little about what is going on, is it "time travel?" is it "reanimating dead tissue?" I have know idea from your logline.

However it could also be a great idea, I just don't know enough about the story from this logline.

Good luck with this!