When Annie's parents' neighbor Mark tells her he has a Sybian, she doesn't know what that is, but when she gets back to college and looks it up, she becomes obsessed with the idea of riding one. Once she's back home on summer vacation, the opportunity arises when Mark leaves town and she's house-sitting for him.
But riding the Sybian is the least of Annie's dark fantasies, and when Mark returns and she finds out he has cameras down in his basement where the Sybian is located, she has an opportunity to live out more of her fantasies. She offers a trade: she'll ride the Sybian in front of Mark, live, if he'll delete the videos of her. Mark accepts the trade and Annie dives into an erotic, perverse rabbithole of sex for Sybian rides, pleasure for pleasure, and her darkest fantasies come true.
Annie and the Sybian is an erotica novel, approximately 25,150k words with a horny eighteen year old, and a HFN ending. It is NOT a romance. Annie's adventures will continue when she goes back to college. There is no cliffhanger.