In 2031, the United States has fallen apart, splintering into several smaller nation states after a period of intense fighting. The now independent California is still not without danger, but things have settled down enough that LA’s curfews have been lifted and people are once again venturing out to have fun. It is in that spirit that Ari convinces her roommate Gloria—afraid to leave their apartment after surviving a terrorist attack—to come with her to a party they were invited to at her friend Kareem’s. The evening seems to be going well, but partway through it almost appears as if duplicate versions of two of the guests have suddenly appeared. Then, after he becomes notably aloof and disconcerted, Kareem vanishes and is never heard from again.

Over the following decades, Ari leaves Los Angeles, making her way to the Midwest and then Europe, taking whatever employment she can find to try and survive, much of it dangerous. But no matter where she goes the strangeness of that night never leaves her.

In another version of our world, the USA remains intact but is watched over by a strict, authoritarian government. There is another version of Ari there, one who never got involved in crime, instead serving as a detective. Unbeknownst to either woman, that fateful night linked their lives in ways that can never be truly known, but which will set them each on a path towards greater understanding of themselves and humanity.

This stunning novel so deftly packs in so much story and so many ideas that it feels almost miraculous. Mandel steers us across decades, continents, and timelines with grace and ease, elegantly doling out information in a manner that makes her people and places easy to picture without bogging us down in extraneous details. You will care about these characters and worry over their fates as the time-and-space-hopping narrative is gradually filled in.

The two extremes on display in the dueling Americas leave the reader yearning for calmer heads to prevail and steer our own world away from either outcome, though both feel all too possible. More than that though, this is a book about connection and beauty and appreciating both when we find them, no matter how fleeting they may be. Our lives may not go the way we want, but we can and should do our best to improve the things we can and see the good in what we get. Packed to the brim with thrilling ideas, Exit Party could keep a book club engaged in lively debate for hours, and will go down as a high point in a year already filled with great books. ★★★★★