Again Again takes place in the same setting as Lockhart's The Disreputable History of Frankie Landau-Banks, Alabaster Preparatory Academy, though Again Again has a different protagonist, Adelaide Buchwald.

The book follows Adelaide through a multiverse of opportunities over the summer between her junior and senior year of high school as she connects with a boy who once wrote a poem about her; the novel investigates the different ways their relationship might play out.

"[3] Again Again was generally well-received by critics, including starred reviews from Booklist,[4] The Bulletin of the Center for Children's Books,[5] School Library Journal.

"[7] Publishers Weekly highlighted Lockhart's skill with plot twists, stating that Again Again takes the technique to a "new level, with a narrative that explores the idea of the multiverse, those infinite worlds loosed by paths taken and not taken.

"[8] Shelf Awareness commented on the book's "unusual" style, explaining how "alternate details of the relationship ... unfold along parallel routes, much like a choose-your-own-ending story, except 'you' don't get to choose--Lockhart does.