One, Two, Buckle My Shoe

Hercule Poirot dislikes his dentist, but one of his patients likes Mr Morley even less - and shoots him minutes after Poirot leaves his surgery. Was it the unpleasant Greek, the wild young American who looked like a murderer, or the former actress with the buckle on her shoe?

have grudge againest

wild goose chase, pompous, dowdy, scraped up an acquaintance

If you say you can't make an omelette without breaking eggs, you mean that it is impossible to achieve something important without there being some bad effects.