Whilst on a quest to capture the legendary Bunyip, an amateur botanist uncovers a small town’s dark secret that he probes at his peril.

Not bad. The Bunyip doesn’t mean anything to me as a word, so perhaps a better replacement would be the same format as for the main character (role and description), but that’s just me. It seems the core of the story is about the town’s dark secret and him probing it, so perhaps the Bunyip is unneccesary? Is this a famous man?
Ah… I just Googled it. I’d suggest if you’re going for a broader, not just Australian audience, you may want a description like, “legendary cryptid, Bunyip.”

So there’s an inciting event – uncovering a small town’s dark secret… obviously the botanist is at peril for probing it – I like that, but the last six words fall flat for me because I’m not getting a sense of what’s more specifically at stake for him, other than general peril, which is harder to connect to emotionally.
(I feel general things like peril, death, etc. are harder to connect with than more specific things that the character faces or wants – like: “he’ll face eternal damnation”… “to get his kids back”…”to try to earn the love of his father”… “to achieve his lifelong dream of becoming a karate master”…etc.)

Why can’t he walk away from this town? Does he have to overcome anything on this quest? Why does this quest or the town’s secret matter to him personally?

So… an amateur botanist uncovers a small town’s dark secret and is compelled to probe further because/when/….

i.e.;
… an amateur botanist uncovers a small town’s dark secret and despite the peril, he probes further in hope to solve the mysterious disappearance his closest childhood friend.

…When an amateur botanist stumbles on a small town’s dark secret during his quest to capture the Bunyip, he falls in love with the local librarian but will face a terrible decision when he discovers she’s the very cryptid he’s been hunting.

Haha, obviously those examples could be way better, but hopefully it kick starts the imagination as how to explain why it matters to him. I’m intrigued, personally. I like stories with cryptids. 😉