The entire plot of this middle grade fiction book hinges on a twelve year old kiss, that is, a kiss between two twelve year olds. I don’t usually like romantic relationships and crushes in middle grade fiction, but for this book I’ll make an exception. It’s a chaste, almost accidental, kiss, and the rest of the book is squeaky clean—and fun, and even thought-provoking.

Two boys, Mason and Ty, have been best friends practically since birth, at least as far back as they can remember. They are both nerds, and proud of it, interested in science projects and video games and time travel, not girls —until Ava, the new girl from New York, comes to town and gets the attention of both boys. Can their friendship survive crushing on the same girl at the same time?

SPOILER: The friendship doesn’t survive, and when both boys (and Ava) are in high school, senior year, things get much, much worse for Mason, all because of the kissing incident that broke up Mason’s friendship with Ty in seventh grade. I guess the central question of the book is: if you could pinpoint one decision that made your life go in the wrong direction and if you had a chance to go back in time and correct that bad decision, would you and could you?

Time travel done well is always fun, and this book does it well. (Although I didn’t really know what Madame Zeynab was supposed to be doing to add to the story . . .) I read somewhere that this is Gordon Korman’s 99th published book, and he has certainly hit his stride and then some. Mr. Korman entertains readers with mid-list middle grade fiction that might just make a few kids think about the impact of seemingly simple decisions and the value of an enduring friendship. 99 books published, he’s got to be doing something right.