Emma Woods is a community college adjunct who floats wherever the current of her life takes her. The only real fire in Emma's life is her yearly trek to the Jane Austen Festival in Bath, the matchstick being Mark Landen, a British bookseller and academic with whom Emma has had a long-standing flirtation neither have pursued due to distance and being in and out of other relationships. However, Mark has written to Emma prior to the upcoming festival to tell her he is unattached and hoping to pursue a relationship. Just before this revelation, though, Emma receives a proposal from her long-time on-again, off-again boyfriend. When Mark feels betrayed by the announcement of Emma's engagement at a dinner amongst all their festival friends, and Emma feels betrayed on discovering Mark drunkenly shagged the woman who delivers that announcement, the two argue on the bridge over the Avon River and fall in.

When they emerge, they discover they have not only gone back in time, but the two women helping them are none other than Jane and Cassandra Austen. Trouble compounds when Mark is mistaken for a clergyman (due to his festival costume) and drafted to fill an empty post in the parish, while Emma is mistaken for an American heiress. Worse still, Emma compulsively quotes lines from Austen's novels to Jane Austen herself, novels which haven't been written yet, resulting in a highly annoyed universe which floods the river they need to use as a portal to return home. Mark finds himself in a love triangle between the parish warden's daughter and the missing clergyman, eventually starting to fade right out of history as they inadvertently change the past. Emma must invoke the prowess of her namesake, Emma Woodhouse, and rematch the warden's daughter to the newly arrived clergyman while avoiding a number of romantic entanglements herself, all of which results in romantic hijinks of Austenian quality that also put her at risk of losing Mark's affection, and even Mark himself. This novel combines drama and comedy to develop rich themes of romance and historicism, and is ultimately about identify, safety vs. risk, and the responsibility we all must take for the choices we make.