Silver Chary, a town guard planning to join the E.U.P suddenly found himself trying to solve mysterious cases of bizzare and gruesome deaths which started out of the blue.
However, while he did got some helping hands from a few ponies who are willing to break the rules of the local authorities of his town, the mystery increases. Will Silver find out the truth behind the bizarre death occurrences, and what fate awaits the peaceful tourist town of Richville?
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It's an interesting start. Given the tags, I presume the flowers weren't as harmless as they think, though remember that it's good to hint at that in the story's opening. (Taking your pacing and set-up into consideration, it could most likely happen at the end of the prologue. The hint that's currently there works as a hint only if one looks for it.) The issue is that right now, this feels like an opening to a cutesy slice of life story about four friends doing something, and unless I paid mind to the tags, I would think that nothing more's going to follow.
Regarding the prologue itself, you didn't make it exactly easy on yourself. Introducing the story, four new OCs, and simulatenously trying to have the characters interact with each other casually, all of that in around 700 words... that's pretty challenging. Still, I'd say you did rather well, even though it wouldn't hurt to set up the scene a bit better (e.g. the characters mention gathering in a park in one instance, though the readers have no idea if they are actually in a park or somewhere else), and you might also keep a close eye on how the characters interact and if everything they say is necessary, since some parts felt rather chaotic and seemed to meander rather than progress. Grammar and spelling-wise, the story does rather well. There are some random issues here and there (one slip into present tense, a missing apostrophe, incorrect syntax, et cetera), though the most obvious issue are recurring errors with punctuation and capitalisation in direct speech and its associated tags. I want to keep this comment moderately short, so I won't go into detail here, but if you want, I can send you a guide on how to do this the right way.