"Help!" a budding novelist asks, hoping to get some advice on a novel. "I'm in a contest and my entry has to be summed up in just one sentence."
Summary is a mighty task. Your book of 70,000 words must be reduced to maybe 35. You can do it, but it's going to demand several revisions. Your first try might be a 50-word sentence. Too long. You don't want your sentence to be over-packed with clauses, either.
Your model ought to establish a character's main desire by showing an inciting event, then establish the character's action the book will tell in its story. I also want to see who opposes the character and get a hint at the resolution.
This is as good a time as any to check your structure. In Story Engineering, Larry Brooks shares a test for whether an idea is fleshed out enough to make a story.
[When] some event sparks a character to action, that [character acts] with deliberate purpose [until] that action is opposed by an external force, [leading to] a conclusion.
You can use a descriptor (amateur botanist) in the character section of the sentence. You're reaching for sizzle in the inciting incident, something dramatic. That's your hook. Your opposing force is your villain, the character whose job is to stop the hero from her goal.
Your goal? To write a sentence that effectively conveys the emotion and entertainment of your book. Bryan Cohen, who advises authors on how to sell their books, has a useful article on this at Amazon Author Insights.
One last bit of how-to. Be ruthless about what you include in your sentence. Does the element illuminate emotion, or convey entertainment? Leave it in. Help a reader desire your story.