Beth thinks a casual encounter with a stranger at a party is a one-time thing, but he seems to have other plans.
She is a brilliant young mathematics professor, and he turns out to be one of her students. Sleeping with him is against her college's rules, and may have a grave professional cost, but Beth is attracted enough to Ethan that she simply doesn't care. She breaks the rules, and sees him again, and begins to realize that she has become too lost in her work and forgotten how wonderful such moments can be.
No-one is getting hurt, she thinks, and no harm is being done, so she sees no reason not to have her fun.
Unfortunately, Beth is also in a long-term, long-distance, very off and on relationship that suddenly turns out to be on again. Robert is moving to be near her, to live with her, and although she doesn't want to give up sex with Ethan, she owes Robert something too.
She can’t simply tell Robert they are done.
She decides to be selfish and keep everything secret. Because she wants to put herself first, and because what Robert doesn't know won't hurt him, and because by keeping secrets she may, in the end, hurt everyone less.
But mostly because she still wants Ethan, and doesn't seem to be able to make herself stop.
One Plus Two Minus One is a novel of lust and desire, of the sensuality and confusion of meeting someone new, of the chaos and harm that secrets can cause, of avoiding choices, and making choices, and of foolishly hoping things will work out for the best.
This is a work of erotica and contains some adult content.