Thanks for taking the time to answer the basic questions, ?decompose the story into it's primary elements. ?This clarifies the through line of the plot.
Unfortunately, there is one big knot in the through line I am unable to untie and straighten out. I am unable to suspend disbelief and buy into the "diablous ex machina" trope, that the poison causes the protagonist to merely shrink instead of die.
A "diabolous ex machina" trope is the reverse of the "deus ex machina" trope. ?The 'deus" trope involves some arbitrary person, object or event that appears out of the ?nowhere with no explanation, setup or foreshadowing ?and saves the day for the protagonist. In ?contrast, the "diabolus" trope entails some arbitrary person, object or event that appears out of nowhere with no explanation , setup or foreshadowing and?ruins the day?for the protagonist.
Of course, ?you can't explain every critical element of a plot in a logline. ?And?a screenwriter has license to introduce novel and strange elements in the first Act ?(only) of the script ?But before you can use ye ol' "Incredible Shrinking Man" gimmick in the script, you gotta waste valuable page space explaining how it is possible. ?Who concocted the poison? ?Why?
?(And because it's being used, the proper genre to describe the story is either SciFi or Fantasy ?rather than crime.)
A logline should raise curiosity, not questions. ?Unfortunately, the "diabolus ex machina" in this premise, the "shrinking" poison raises more questions than curiosity in my mind. ?Like: ?Why, ?for the purpose of this story, must the character shrink? ?What's the dramatic point of shrinking the character other than making the plot more difficult for him? ?What theme are you trying to explore with this 'diabolous ex machina' trope?
Other people may respond differently, have no problem no questions about the "diabolus" trope. ?But I do.
fwiw