Figuring out the plot is the easy part.

Applying your ass to a chair and your fingers to a keyboard (without glancing at Susan's every five minutes) for months and months to get your 80,000 words is the hard part, and that's just a first draft that you'll look at and want to throw in the trash because it's so bad (and if you look at your first draft and think, "That's a wrap!" rather than, "Oh my god, I can't write!", there's a problem.) Then the real writing begins; redraft after redraft after redraft. In a year or two, depending on your commitment, you'll have a serviceable novel that you'll be able to send out to agents. Then sit back and watch the rejection letters pile up if they can even be bothered to reply. If you're extremely lucky, an agent will want to take a chance on you. If you're extremely, extremely lucky, your agent will be able to sell your manuscript to a legit publisher. Then if you're extremely, extremely,
extremely lucky, your novel will sell a few hundred copies.
That's a
success story in modern publishing.
You could go to the Amazon self published route, but in reality 99.9% of those books are truly terrible and it'll be hard to convince anybody that yours is anything different.
Yup, Brenda the frustrated novelist...