>>but quickly discovered it has been done before.
For instance?
>>>?When a drug lord holds his brother to ransom over a stolen shipment, a callous criminal with face blindness enlists the aid of other people with rare neurological disorders to track down his psychopathic ex-accomplice and retrieve the drugs.?
Frankly -- one reader's opinion -- I'm not (yet) sold on the plot.? But I was sold on the hook of face blindness from the first reading.? Even though I believe it's a story hook that may be challenging for a logline reader to swallow and digest.?
Plot issues aside,? I suggest you consider polishing the logline in two respects: 1] The ideal word length for a logline is 25 words.? Your latest iteration is 39 words long.? ?2] The story hook should either lead off or be the? concluding "button" or punch phrase .? In this iteration, the story hook --face blindness -- is buried n the middle.
>>> I like the idea that the face blindness causes/represents a deeper moral flaw, e.g. misanthropy or callousness.
Which is the chicken, which is the egg?? Does the face blindness cause his callousness -- or does it enable it?
fwiw